Key Concepts

• The counting numbers start with 1 and continue: [latex]1,2,3,4,5\dots[/latex].
• The whole numbers are the counting numbers and zero: [latex]0,1,2,3,4,5\ldots[/latex].
• When rounding numbers, look to the digit to the right of the place value to which the number should be rounded. If it is 5 or greater, increase the digit in the place value to which you are rounding by one and replace the position to the right with a zero. If 4 or less, do not change the place value to which you are rounding but do replace the position to the right with a zero.

Key Equations

• Identity property of addition: [latex]a+0=a[/latex].
• Commutative property of addition: [latex]a+b=b+a[/latex].
• Identity property of multiplication: [latex]a\cdot 1=a[/latex].
• Commutative property of multiplication: [latex]a\cdot b=b\cdot a[/latex].
• Multiplication property of zero: [latex]a\cdot 0=0[/latex].
• Division properties of one: [latex]a\div a=1[/latex] and [latex]a\div 1=a[/latex].
• Division properties of zero: [latex]0\div a=0[/latex] and [latex]a\div 0=\text{undefined}[/latex]..

Glossary

difference

the result of subtracting

product

the result of multiplying

quotient

the result of dividing

rounding

to approximate the value of a number to a particular place value

sum

the result of adding