{"id":4629,"date":"2020-04-21T00:19:11","date_gmt":"2020-04-21T00:19:11","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/chapter\/dividing-fractions\/"},"modified":"2020-04-21T00:19:11","modified_gmt":"2020-04-21T00:19:11","slug":"dividing-fractions","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/chapter\/dividing-fractions\/","title":{"raw":"Dividing Fractions","rendered":"Dividing Fractions"},"content":{"raw":"\n<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n \t<li>Divide fractions\n<ul>\n \t<li>Find the reciprocal of a number<\/li>\n \t<li>Divide a fraction by a whole number<\/li>\n \t<li>Divide a fraction by a fraction<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/div>\n<h2>Introduction<\/h2>\nBefore we get started, here is some important terminology that will help you understand the concepts about working with fractions in this section.\n<ul>\n \t<li><strong>product:&nbsp;<\/strong>the result of &nbsp;multiplication<\/li>\n \t<li><strong>factor:<\/strong> something being multiplied - for &nbsp;[latex]3 \\cdot 2 = 6[\/latex] , both 3 and 2 are factors of 6<\/li>\n \t<li><strong>numerator:<\/strong> the top part of a fraction - the numerator in the fraction&nbsp;[latex]\\frac{2}{3}[\/latex] is 2<\/li>\n \t<li><strong>denominator:<\/strong> the bottom part of a fraction - the denominator in the fraction&nbsp;[latex]\\frac{2}{3}[\/latex] is 3<\/li>\n<\/ul>\n<h2>Note About Instructions<\/h2>\nMany different words are used by math textbooks and teachers to provide students with instructions on what they are to do with a given problem. For example, you may see instructions such as \"Find\" or \"Simplify\" in the example in this module. It is important to understand what these words mean so you can successfully work through the problems in this course. Here is a short list of the words you may see that can help you know how to work through the problems in this module.\n<table>\n<thead>\n<tr>\n<th>Instruction<\/th>\n<th>Interpretation<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Find<\/td>\n<td>Perform the indicated mathematical operations which may include addition, subtraction, multiplication, division.<\/td>\n<\/tr>\n<tr>\n<td>Simplify<\/td>\n<td>1) Perform the indicated mathematical operations including addition, subtraction, multiplication, division\n\n2) Write a mathematical statement in smallest terms so there are no other mathematical operations that can be performed\u2014often found in problems related to fractions and the order of operations<\/td>\n<\/tr>\n<tr>\n<td>Evaluate<\/td>\n<td>Perform the indicated mathematical operations including addition, subtraction, multiplication, division<\/td>\n<\/tr>\n<tr>\n<td>Reduce<\/td>\n<td>Write a mathematical statement in smallest or lowest terms so there are no other mathematical operations that can be performed\u2014often found in problems related to fractions or division<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>Divide Fractions<\/h2>\nThere are times when you need to use division to solve a problem. For example, if painting one coat of paint on the walls of a room requires 3 quarts of paint and you have&nbsp;a bucket that contains 6 quarts of paint, how many coats of paint can you paint on the walls? You divide 6 by 3 for an answer of 2 coats. There will also be times when you need to divide by a fraction. Suppose painting a closet with one coat only required [latex] \\frac{1}{2}[\/latex] quart of paint. How many coats could be painted with the 6 quarts of paint? To find the answer, you need to divide 6 by the fraction, [latex] \\frac{1}{2}[\/latex].\n\nBefore we begin dividing fractions, let's cover some important terminology.\n<ul>\n \t<li><strong>reciprocal:<\/strong> two fractions are reciprocals if their product is 1 (Don't worry; we will show you examples of what this means.)<\/li>\n \t<li><strong>quotient:<\/strong> the result&nbsp;of division<\/li>\n<\/ul>\nDividing fractions requires using the reciprocal of a number or fraction. If you multiply two numbers together and get 1 as a result, then the two numbers are reciprocals. Here are some examples of reciprocals:\n<table>\n<thead>\n<tr>\n<th>Original number<\/th>\n<th>Reciprocal<\/th>\n<th>Product<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>[latex] \\frac{3}{4}[\/latex]<\/td>\n<td>[latex] \\frac{4}{3}[\/latex]<\/td>\n<td>[latex] \\frac{3}{4}\\cdot \\frac{4}{3}=\\frac{3\\cdot 4}{4\\cdot 3}=\\frac{12}{12}=1[\/latex]<\/td>\n<\/tr>\n<tr>\n<td>[latex] \\frac{1}{2}[\/latex]<\/td>\n<td>[latex] \\frac{2}{1}[\/latex]<\/td>\n<td>[latex]\\frac{1}{2}\\cdot\\frac{2}{1}=\\frac{1\\cdot}{2\\cdot1}=\\frac{2}{2}=1[\/latex]<\/td>\n<\/tr>\n<tr>\n<td>[latex] 3=\\frac{3}{1}[\/latex]<\/td>\n<td>[latex] \\frac{1}{3}[\/latex]<\/td>\n<td>[latex] \\frac{3}{1}\\cdot \\frac{1}{3}=\\frac{3\\cdot 1}{1\\cdot 3}=\\frac{3}{3}=1[\/latex]<\/td>\n<\/tr>\n<tr>\n<td>[latex]2\\frac{1}{3}=\\frac{7}{3}[\/latex]<\/td>\n<td>[latex] \\frac{3}{7}[\/latex]<\/td>\n<td>[latex]\\frac{7}{3}\\cdot\\frac{3}{7}=\\frac{7\\cdot3}{3\\cdot7}=\\frac{21}{21}=1[\/latex]<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\nSometimes we call&nbsp;the reciprocal&nbsp;the \u201cflip\u201d of the other number: flip [latex] \\frac{2}{5}[\/latex] to get the reciprocal [latex]\\frac{5}{2}[\/latex].\n\n&nbsp;\n<h2>Division by Zero<\/h2>\nYou know what it means to divide by 2 or divide by 10, but what does it mean to divide a quantity by 0? Is this even possible? Can you divide 0 by a number? Consider the&nbsp;fraction\n<p style=\"text-align: center;\">[latex]\\frac{0}{8}[\/latex]<\/p>\nWe can read it as, \u201czero divided by eight.\u201d Since multiplication is the inverse of division, we could rewrite this as a multiplication problem.\n<p style=\"text-align: center;\">[latex]\\text{?}\\cdot{8}=0[\/latex].<\/p>\n<p style=\"text-align: left;\">We can infer that the unknown must be 0 since that is the only number that will give a result of 0 when it is multiplied by 8.<\/p>\nNow let\u2019s consider the reciprocal of [latex]\\frac{0}{8}[\/latex] which would be [latex]\\frac{8}{0}[\/latex]. If we&nbsp;rewrite this as a multiplication problem, we will have\n<p style=\"text-align: center;\">[latex]\\text{?}\\cdot{0}=8[\/latex].<\/p>\nThis doesn't make any sense. There are no numbers that you can multiply by zero to get a result of 8. The reciprocal of&nbsp;[latex]\\frac{8}{0}[\/latex] is undefined, and in fact, all division by zero is undefined.\n\n<div class=\"textbox shaded\"><p><img class=\"wp-image-2132 alignleft\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1468\/2016\/03\/22011815\/traffic-sign-160659-300x265.png\" alt=\"Caution\" width=\"62\" height=\"55\">Caution! Division by zero is undefined and so is the reciprocal of any fraction that has a zero in the numerator. For any real number a, [latex]\\frac{a}{0}[\/latex] is undefined. Additionally, the reciprocal of&nbsp;[latex]\\frac{0}{a}[\/latex] will always be undefined.<\/p><\/div>\n\n<h2>Divide a Fraction by a Whole Number<\/h2>\nWhen you divide by a whole number, you are multiplying by the reciprocal. In the painting example where you need 3 quarts of paint for a coat and have 6 quarts of paint, you can find the total number of coats that can be painted by dividing 6 by 3, [latex]6\\div3=2[\/latex]. You can also multiply 6 by the reciprocal of 3, which is [latex] \\frac{1}{3}[\/latex], so the multiplication problem becomes\n<p style=\"text-align: center;\">[latex] \\frac{6}{1}\\cdot \\frac{1}{3}=\\frac{6}{3}=2[\/latex].<\/p>\n&nbsp;\n<div class=\"textbox shaded\">\n<h3>Dividing is Multiplying by the Reciprocal<\/h3>\nFor all division, you can turn the operation&nbsp;into multiplication by using the reciprocal. Dividing is the same as multiplying by the reciprocal.\n\n<\/div>\nThe same idea will work when the divisor (the thing being divided) is a fraction. If you have [latex] \\frac{3}{4}[\/latex] of a candy bar and need to divide it among 5 people, each person gets [latex] \\frac{1}{5}[\/latex] of the available candy:\n<p style=\"text-align: center;\">[latex] \\frac{1}{5}\\text{ of }\\frac{3}{4}=\\frac{1}{5}\\cdot \\frac{3}{4}=\\frac{3}{20}[\/latex]<\/p>\n<p style=\"text-align: center;\">Each person gets [latex]\\frac{3}{20}[\/latex]&nbsp;of a whole candy bar.<\/p>\nIf you have a recipe that needs to be divided in half, you can divide each ingredient by 2, or you can multiply each ingredient by [latex]\\frac{1}{2}[\/latex]&nbsp;to find the new amount.\n\nFor example, dividing by 6 is the same as multiplying by the reciprocal of 6, which is [latex]\\frac{1}{6}[\/latex]. Look at the diagram of two pizzas below. &nbsp;How can you divide what is left (the red shaded region) among 6 people fairly?\n\n<img class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1468\/2016\/03\/17170720\/image143.gif\" alt=\"Two pizzas divided into fourths. One pizza has all four pieces shaded, and the other pizza has two of the four slices shaded. 3\/2 divided by 6 is equal to 3\/2 times 1\/6. This is 3\/2 times 1\/6 equals 1\/4.\" width=\"360\" height=\"239\">\n\nEach person gets one piece, so each person gets [latex] \\frac{1}{4}[\/latex] of a pizza.\n\nDividing a fraction by a whole number is the same as multiplying by the reciprocal, so you can always use multiplication of fractions to solve division problems.\n<div class=\"bcc-box bcc-info\">\n<h3>Example<\/h3>\nFind [latex] \\frac{2}{3}\\div 4[\/latex].\n\n[reveal-answer q=\"769187\"]Show Solution[\/reveal-answer]\n[hidden-answer a=\"769187\"]Write your answer in lowest terms.\n\nDividing by 4 or [latex] \\frac{4}{1}[\/latex] is the same as multiplying by the reciprocal of 4, which is [latex] \\frac{1}{4}[\/latex].\n<p style=\"text-align: center;\">[latex] \\frac{2}{3}\\div 4=\\frac{2}{3}\\cdot \\frac{1}{4}[\/latex]<\/p>\nMultiply numerators and multiply denominators.\n<p style=\"text-align: center;\">[latex] \\frac{2\\cdot 1}{3\\cdot 4}=\\frac{2}{12}[\/latex]<\/p>\nSimplify to lowest terms by dividing numerator and denominator by the common factor 4.\n<p style=\"text-align: center;\">[latex] \\frac{1}{6}[\/latex]<\/p>\n\n<h4>Answer<\/h4>\n[latex]\\frac{2}{3}\\div4=\\frac{1}{6}[\/latex]\n\n[\/hidden-answer]\n\n<\/div>\n<div class=\"bcc-box bcc-info\">\n<h3>Example<\/h3>\nDivide. [latex] 9\\div\\frac{1}{2}[\/latex].\n\n[reveal-answer q=\"269187\"]Show Solution[\/reveal-answer]\n[hidden-answer a=\"269187\"]Write your answer in lowest terms.\n\nDividing by [latex]\\frac{1}{2}[\/latex] is the same as multiplying by the reciprocal of [latex]\\frac{1}{2}[\/latex], which is [latex] \\frac{2}{1}[\/latex].\n<p style=\"text-align: center;\">[latex]9\\div\\frac{1}{2}=\\frac{9}{1}\\cdot\\frac{2}{1}[\/latex]<\/p>\nMultiply numerators and multiply denominators.\n<p style=\"text-align: center;\">[latex] \\frac{9\\cdot 2}{1\\cdot 1}=\\frac{18}{1}=18[\/latex]<\/p>\nThis answer is already simplified to lowest terms.\n<h4>Answer<\/h4>\n[latex]9\\div\\frac{1}{2}=18[\/latex]\n\n[\/hidden-answer]\n\n<\/div>\n<h2>Divide a Fraction by a Fraction<\/h2>\nSometimes you need to solve a problem that requires dividing by a fraction. Suppose you have a pizza that is already cut into 4 slices. How many [latex]\\frac{1}{2}[\/latex] slices are there?\n<table>\n<tbody>\n<tr>\n<td><img class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1468\/2016\/03\/17170724\/image146.gif\" alt=\"A pizza divided into four equal pieces. There are four slices.\" width=\"180\" height=\"179\"><\/td>\n<td><img class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1468\/2016\/03\/17170725\/image147.gif\" alt=\"A pizza divided into four equal slices. Each slice is then divided in half. There are now 8 slices. \" width=\"180\" height=\"179\"><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\nThere are 8 slices. You can see that dividing 4 by [latex] \\frac{1}{2}[\/latex] gives the same result as multiplying 4 by 2.\n\nWhat would happen if you needed to divide each slice into thirds?\n\n<img class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1468\/2016\/03\/17170726\/image148.gif\" alt=\"A pizza divided into four equal slice. Each slice is divided into thirds. There are now 12 slices.\" width=\"180\" height=\"179\">\n\nYou would have 12 slices, which is the same as multiplying 4 by 3.\n<div class=\"textbox shaded\">\n<h3>Dividing with Fractions<\/h3>\n<ol>\n \t<li>Find the reciprocal of the number that follows the division symbol.<\/li>\n \t<li>Multiply the first number (the one before the division symbol) by the reciprocal of the second number (the one after the division symbol).<\/li>\n<\/ol>\n<\/div>\nAny easy way to remember how to divide fractions is the phrase \u201ckeep, change, flip.\u201d This means to <strong>KEEP<\/strong> the first number, <strong>CHANGE<\/strong> the division sign to multiplication, and then <strong>FLIP<\/strong> (use the reciprocal) of the second number.\n<div class=\"bcc-box bcc-info\">\n<h3>Example<\/h3>\nDivide [latex] \\frac{2}{3}\\div \\frac{1}{6}[\/latex].\n\n[reveal-answer q=\"569112\"]Show Solution[\/reveal-answer]\n[hidden-answer a=\"569112\"]Multiply by the reciprocal.\n\n<strong>KEEP<\/strong> [latex] \\frac{2}{3}[\/latex]\n\n<strong>CHANGE<\/strong>&nbsp; [latex] \\div [\/latex] to &nbsp;[latex]\\cdot[\/latex]\n\n<strong>FLIP&nbsp;<\/strong> [latex]\\frac{1}{6}[\/latex]\n<p style=\"text-align: center;\">[latex] \\frac{2}{3}\\cdot \\frac{6}{1}[\/latex]<\/p>\nMultiply numerators and multiply denominators.\n<p style=\"text-align: center;\">[latex]\\frac{2\\cdot6}{3\\cdot1}=\\frac{12}{3}[\/latex]<\/p>\n&nbsp;\n\nSimplify.\n<p style=\"text-align: center;\">[latex] \\frac{12}{3}=4[\/latex]<\/p>\n\n<h4>Answer<\/h4>\n[latex] \\frac{2}{3}\\div \\frac{1}{6}=4[\/latex]\n\n[\/hidden-answer]\n\n<\/div>\n<div class=\"bcc-box bcc-info\">\n<h3>Example<\/h3>\nDivide [latex] \\frac{3}{5}\\div \\frac{2}{3}[\/latex].\n\n[reveal-answer q=\"950670\"]Show Solution[\/reveal-answer]\n[hidden-answer a=\"950670\"]Multiply by the reciprocal.&nbsp;Keep [latex] \\frac{3}{5}[\/latex], change [latex] \\div [\/latex] to [latex]\\cdot[\/latex], and flip [latex] \\frac{2}{3}[\/latex].\n<p style=\"text-align: center;\">[latex] \\frac{3}{5}\\cdot \\frac{3}{2}[\/latex]<\/p>\nMultiply numerators and multiply denominators.\n<p style=\"text-align: center;\">[latex] \\frac{3\\cdot 3}{5\\cdot 2}=\\frac{9}{10}[\/latex]<\/p>\n[\/hidden-answer]\n\n<\/div>\n","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Divide fractions\n<ul>\n<li>Find the reciprocal of a number<\/li>\n<li>Divide a fraction by a whole number<\/li>\n<li>Divide a fraction by a fraction<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/div>\n<h2>Introduction<\/h2>\n<p>Before we get started, here is some important terminology that will help you understand the concepts about working with fractions in this section.<\/p>\n<ul>\n<li><strong>product:&nbsp;<\/strong>the result of &nbsp;multiplication<\/li>\n<li><strong>factor:<\/strong> something being multiplied &#8211; for &nbsp;[latex]3 \\cdot 2 = 6[\/latex] , both 3 and 2 are factors of 6<\/li>\n<li><strong>numerator:<\/strong> the top part of a fraction &#8211; the numerator in the fraction&nbsp;[latex]\\frac{2}{3}[\/latex] is 2<\/li>\n<li><strong>denominator:<\/strong> the bottom part of a fraction &#8211; the denominator in the fraction&nbsp;[latex]\\frac{2}{3}[\/latex] is 3<\/li>\n<\/ul>\n<h2>Note About Instructions<\/h2>\n<p>Many different words are used by math textbooks and teachers to provide students with instructions on what they are to do with a given problem. For example, you may see instructions such as &#8220;Find&#8221; or &#8220;Simplify&#8221; in the example in this module. It is important to understand what these words mean so you can successfully work through the problems in this course. Here is a short list of the words you may see that can help you know how to work through the problems in this module.<\/p>\n<table>\n<thead>\n<tr>\n<th>Instruction<\/th>\n<th>Interpretation<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Find<\/td>\n<td>Perform the indicated mathematical operations which may include addition, subtraction, multiplication, division.<\/td>\n<\/tr>\n<tr>\n<td>Simplify<\/td>\n<td>1) Perform the indicated mathematical operations including addition, subtraction, multiplication, division<\/p>\n<p>2) Write a mathematical statement in smallest terms so there are no other mathematical operations that can be performed\u2014often found in problems related to fractions and the order of operations<\/td>\n<\/tr>\n<tr>\n<td>Evaluate<\/td>\n<td>Perform the indicated mathematical operations including addition, subtraction, multiplication, division<\/td>\n<\/tr>\n<tr>\n<td>Reduce<\/td>\n<td>Write a mathematical statement in smallest or lowest terms so there are no other mathematical operations that can be performed\u2014often found in problems related to fractions or division<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>Divide Fractions<\/h2>\n<p>There are times when you need to use division to solve a problem. For example, if painting one coat of paint on the walls of a room requires 3 quarts of paint and you have&nbsp;a bucket that contains 6 quarts of paint, how many coats of paint can you paint on the walls? You divide 6 by 3 for an answer of 2 coats. There will also be times when you need to divide by a fraction. Suppose painting a closet with one coat only required [latex]\\frac{1}{2}[\/latex] quart of paint. How many coats could be painted with the 6 quarts of paint? To find the answer, you need to divide 6 by the fraction, [latex]\\frac{1}{2}[\/latex].<\/p>\n<p>Before we begin dividing fractions, let&#8217;s cover some important terminology.<\/p>\n<ul>\n<li><strong>reciprocal:<\/strong> two fractions are reciprocals if their product is 1 (Don&#8217;t worry; we will show you examples of what this means.)<\/li>\n<li><strong>quotient:<\/strong> the result&nbsp;of division<\/li>\n<\/ul>\n<p>Dividing fractions requires using the reciprocal of a number or fraction. If you multiply two numbers together and get 1 as a result, then the two numbers are reciprocals. Here are some examples of reciprocals:<\/p>\n<table>\n<thead>\n<tr>\n<th>Original number<\/th>\n<th>Reciprocal<\/th>\n<th>Product<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>[latex]\\frac{3}{4}[\/latex]<\/td>\n<td>[latex]\\frac{4}{3}[\/latex]<\/td>\n<td>[latex]\\frac{3}{4}\\cdot \\frac{4}{3}=\\frac{3\\cdot 4}{4\\cdot 3}=\\frac{12}{12}=1[\/latex]<\/td>\n<\/tr>\n<tr>\n<td>[latex]\\frac{1}{2}[\/latex]<\/td>\n<td>[latex]\\frac{2}{1}[\/latex]<\/td>\n<td>[latex]\\frac{1}{2}\\cdot\\frac{2}{1}=\\frac{1\\cdot}{2\\cdot1}=\\frac{2}{2}=1[\/latex]<\/td>\n<\/tr>\n<tr>\n<td>[latex]3=\\frac{3}{1}[\/latex]<\/td>\n<td>[latex]\\frac{1}{3}[\/latex]<\/td>\n<td>[latex]\\frac{3}{1}\\cdot \\frac{1}{3}=\\frac{3\\cdot 1}{1\\cdot 3}=\\frac{3}{3}=1[\/latex]<\/td>\n<\/tr>\n<tr>\n<td>[latex]2\\frac{1}{3}=\\frac{7}{3}[\/latex]<\/td>\n<td>[latex]\\frac{3}{7}[\/latex]<\/td>\n<td>[latex]\\frac{7}{3}\\cdot\\frac{3}{7}=\\frac{7\\cdot3}{3\\cdot7}=\\frac{21}{21}=1[\/latex]<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Sometimes we call&nbsp;the reciprocal&nbsp;the \u201cflip\u201d of the other number: flip [latex]\\frac{2}{5}[\/latex] to get the reciprocal [latex]\\frac{5}{2}[\/latex].<\/p>\n<p>&nbsp;<\/p>\n<h2>Division by Zero<\/h2>\n<p>You know what it means to divide by 2 or divide by 10, but what does it mean to divide a quantity by 0? Is this even possible? Can you divide 0 by a number? Consider the&nbsp;fraction<\/p>\n<p style=\"text-align: center;\">[latex]\\frac{0}{8}[\/latex]<\/p>\n<p>We can read it as, \u201czero divided by eight.\u201d Since multiplication is the inverse of division, we could rewrite this as a multiplication problem.<\/p>\n<p style=\"text-align: center;\">[latex]\\text{?}\\cdot{8}=0[\/latex].<\/p>\n<p style=\"text-align: left;\">We can infer that the unknown must be 0 since that is the only number that will give a result of 0 when it is multiplied by 8.<\/p>\n<p>Now let\u2019s consider the reciprocal of [latex]\\frac{0}{8}[\/latex] which would be [latex]\\frac{8}{0}[\/latex]. If we&nbsp;rewrite this as a multiplication problem, we will have<\/p>\n<p style=\"text-align: center;\">[latex]\\text{?}\\cdot{0}=8[\/latex].<\/p>\n<p>This doesn&#8217;t make any sense. There are no numbers that you can multiply by zero to get a result of 8. The reciprocal of&nbsp;[latex]\\frac{8}{0}[\/latex] is undefined, and in fact, all division by zero is undefined.<\/p>\n<div class=\"textbox shaded\">\n<p><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2132 alignleft\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1468\/2016\/03\/22011815\/traffic-sign-160659-300x265.png\" alt=\"Caution\" width=\"62\" height=\"55\" \/>Caution! Division by zero is undefined and so is the reciprocal of any fraction that has a zero in the numerator. For any real number a, [latex]\\frac{a}{0}[\/latex] is undefined. Additionally, the reciprocal of&nbsp;[latex]\\frac{0}{a}[\/latex] will always be undefined.<\/p>\n<\/div>\n<h2>Divide a Fraction by a Whole Number<\/h2>\n<p>When you divide by a whole number, you are multiplying by the reciprocal. In the painting example where you need 3 quarts of paint for a coat and have 6 quarts of paint, you can find the total number of coats that can be painted by dividing 6 by 3, [latex]6\\div3=2[\/latex]. You can also multiply 6 by the reciprocal of 3, which is [latex]\\frac{1}{3}[\/latex], so the multiplication problem becomes<\/p>\n<p style=\"text-align: center;\">[latex]\\frac{6}{1}\\cdot \\frac{1}{3}=\\frac{6}{3}=2[\/latex].<\/p>\n<p>&nbsp;<\/p>\n<div class=\"textbox shaded\">\n<h3>Dividing is Multiplying by the Reciprocal<\/h3>\n<p>For all division, you can turn the operation&nbsp;into multiplication by using the reciprocal. Dividing is the same as multiplying by the reciprocal.<\/p>\n<\/div>\n<p>The same idea will work when the divisor (the thing being divided) is a fraction. If you have [latex]\\frac{3}{4}[\/latex] of a candy bar and need to divide it among 5 people, each person gets [latex]\\frac{1}{5}[\/latex] of the available candy:<\/p>\n<p style=\"text-align: center;\">[latex]\\frac{1}{5}\\text{ of }\\frac{3}{4}=\\frac{1}{5}\\cdot \\frac{3}{4}=\\frac{3}{20}[\/latex]<\/p>\n<p style=\"text-align: center;\">Each person gets [latex]\\frac{3}{20}[\/latex]&nbsp;of a whole candy bar.<\/p>\n<p>If you have a recipe that needs to be divided in half, you can divide each ingredient by 2, or you can multiply each ingredient by [latex]\\frac{1}{2}[\/latex]&nbsp;to find the new amount.<\/p>\n<p>For example, dividing by 6 is the same as multiplying by the reciprocal of 6, which is [latex]\\frac{1}{6}[\/latex]. Look at the diagram of two pizzas below. &nbsp;How can you divide what is left (the red shaded region) among 6 people fairly?<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1468\/2016\/03\/17170720\/image143.gif\" alt=\"Two pizzas divided into fourths. One pizza has all four pieces shaded, and the other pizza has two of the four slices shaded. 3\/2 divided by 6 is equal to 3\/2 times 1\/6. This is 3\/2 times 1\/6 equals 1\/4.\" width=\"360\" height=\"239\" \/><\/p>\n<p>Each person gets one piece, so each person gets [latex]\\frac{1}{4}[\/latex] of a pizza.<\/p>\n<p>Dividing a fraction by a whole number is the same as multiplying by the reciprocal, so you can always use multiplication of fractions to solve division problems.<\/p>\n<div class=\"bcc-box bcc-info\">\n<h3>Example<\/h3>\n<p>Find [latex]\\frac{2}{3}\\div 4[\/latex].<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q769187\">Show Solution<\/span><\/p>\n<div id=\"q769187\" class=\"hidden-answer\" style=\"display: none\">Write your answer in lowest terms.<\/p>\n<p>Dividing by 4 or [latex]\\frac{4}{1}[\/latex] is the same as multiplying by the reciprocal of 4, which is [latex]\\frac{1}{4}[\/latex].<\/p>\n<p style=\"text-align: center;\">[latex]\\frac{2}{3}\\div 4=\\frac{2}{3}\\cdot \\frac{1}{4}[\/latex]<\/p>\n<p>Multiply numerators and multiply denominators.<\/p>\n<p style=\"text-align: center;\">[latex]\\frac{2\\cdot 1}{3\\cdot 4}=\\frac{2}{12}[\/latex]<\/p>\n<p>Simplify to lowest terms by dividing numerator and denominator by the common factor 4.<\/p>\n<p style=\"text-align: center;\">[latex]\\frac{1}{6}[\/latex]<\/p>\n<h4>Answer<\/h4>\n<p>[latex]\\frac{2}{3}\\div4=\\frac{1}{6}[\/latex]<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"bcc-box bcc-info\">\n<h3>Example<\/h3>\n<p>Divide. [latex]9\\div\\frac{1}{2}[\/latex].<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q269187\">Show Solution<\/span><\/p>\n<div id=\"q269187\" class=\"hidden-answer\" style=\"display: none\">Write your answer in lowest terms.<\/p>\n<p>Dividing by [latex]\\frac{1}{2}[\/latex] is the same as multiplying by the reciprocal of [latex]\\frac{1}{2}[\/latex], which is [latex]\\frac{2}{1}[\/latex].<\/p>\n<p style=\"text-align: center;\">[latex]9\\div\\frac{1}{2}=\\frac{9}{1}\\cdot\\frac{2}{1}[\/latex]<\/p>\n<p>Multiply numerators and multiply denominators.<\/p>\n<p style=\"text-align: center;\">[latex]\\frac{9\\cdot 2}{1\\cdot 1}=\\frac{18}{1}=18[\/latex]<\/p>\n<p>This answer is already simplified to lowest terms.<\/p>\n<h4>Answer<\/h4>\n<p>[latex]9\\div\\frac{1}{2}=18[\/latex]<\/p>\n<\/div>\n<\/div>\n<\/div>\n<h2>Divide a Fraction by a Fraction<\/h2>\n<p>Sometimes you need to solve a problem that requires dividing by a fraction. Suppose you have a pizza that is already cut into 4 slices. How many [latex]\\frac{1}{2}[\/latex] slices are there?<\/p>\n<table>\n<tbody>\n<tr>\n<td><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1468\/2016\/03\/17170724\/image146.gif\" alt=\"A pizza divided into four equal pieces. There are four slices.\" width=\"180\" height=\"179\" \/><\/td>\n<td><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1468\/2016\/03\/17170725\/image147.gif\" alt=\"A pizza divided into four equal slices. Each slice is then divided in half. There are now 8 slices.\" width=\"180\" height=\"179\" \/><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>There are 8 slices. You can see that dividing 4 by [latex]\\frac{1}{2}[\/latex] gives the same result as multiplying 4 by 2.<\/p>\n<p>What would happen if you needed to divide each slice into thirds?<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1468\/2016\/03\/17170726\/image148.gif\" alt=\"A pizza divided into four equal slice. Each slice is divided into thirds. There are now 12 slices.\" width=\"180\" height=\"179\" \/><\/p>\n<p>You would have 12 slices, which is the same as multiplying 4 by 3.<\/p>\n<div class=\"textbox shaded\">\n<h3>Dividing with Fractions<\/h3>\n<ol>\n<li>Find the reciprocal of the number that follows the division symbol.<\/li>\n<li>Multiply the first number (the one before the division symbol) by the reciprocal of the second number (the one after the division symbol).<\/li>\n<\/ol>\n<\/div>\n<p>Any easy way to remember how to divide fractions is the phrase \u201ckeep, change, flip.\u201d This means to <strong>KEEP<\/strong> the first number, <strong>CHANGE<\/strong> the division sign to multiplication, and then <strong>FLIP<\/strong> (use the reciprocal) of the second number.<\/p>\n<div class=\"bcc-box bcc-info\">\n<h3>Example<\/h3>\n<p>Divide [latex]\\frac{2}{3}\\div \\frac{1}{6}[\/latex].<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q569112\">Show Solution<\/span><\/p>\n<div id=\"q569112\" class=\"hidden-answer\" style=\"display: none\">Multiply by the reciprocal.<\/p>\n<p><strong>KEEP<\/strong> [latex]\\frac{2}{3}[\/latex]<\/p>\n<p><strong>CHANGE<\/strong>&nbsp; [latex]\\div[\/latex] to &nbsp;[latex]\\cdot[\/latex]<\/p>\n<p><strong>FLIP&nbsp;<\/strong> [latex]\\frac{1}{6}[\/latex]<\/p>\n<p style=\"text-align: center;\">[latex]\\frac{2}{3}\\cdot \\frac{6}{1}[\/latex]<\/p>\n<p>Multiply numerators and multiply denominators.<\/p>\n<p style=\"text-align: center;\">[latex]\\frac{2\\cdot6}{3\\cdot1}=\\frac{12}{3}[\/latex]<\/p>\n<p>&nbsp;<\/p>\n<p>Simplify.<\/p>\n<p style=\"text-align: center;\">[latex]\\frac{12}{3}=4[\/latex]<\/p>\n<h4>Answer<\/h4>\n<p>[latex]\\frac{2}{3}\\div \\frac{1}{6}=4[\/latex]<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"bcc-box bcc-info\">\n<h3>Example<\/h3>\n<p>Divide [latex]\\frac{3}{5}\\div \\frac{2}{3}[\/latex].<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q950670\">Show Solution<\/span><\/p>\n<div id=\"q950670\" class=\"hidden-answer\" style=\"display: none\">Multiply by the reciprocal.&nbsp;Keep [latex]\\frac{3}{5}[\/latex], change [latex]\\div[\/latex] to [latex]\\cdot[\/latex], and flip [latex]\\frac{2}{3}[\/latex].<\/p>\n<p style=\"text-align: center;\">[latex]\\frac{3}{5}\\cdot \\frac{3}{2}[\/latex]<\/p>\n<p>Multiply numerators and multiply denominators.<\/p>\n<p style=\"text-align: center;\">[latex]\\frac{3\\cdot 3}{5\\cdot 2}=\\frac{9}{10}[\/latex]<\/p>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"author":17533,"menu_order":10,"template":"","meta":{"_candela_citation":"[]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-4629","chapter","type-chapter","status-publish","hentry"],"part":4619,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/wp-json\/pressbooks\/v2\/chapters\/4629","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/wp-json\/wp\/v2\/users\/17533"}],"version-history":[{"count":0,"href":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/wp-json\/pressbooks\/v2\/chapters\/4629\/revisions"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/wp-json\/pressbooks\/v2\/parts\/4619"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/wp-json\/pressbooks\/v2\/chapters\/4629\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/wp-json\/wp\/v2\/media?parent=4629"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/wp-json\/pressbooks\/v2\/chapter-type?post=4629"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/wp-json\/wp\/v2\/contributor?post=4629"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/mathforliberalartscorequisite\/wp-json\/wp\/v2\/license?post=4629"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}