Subtracting Whole Numbers: The Inverse Operation of Addition

Learning Outcomes

• Subtract single-digit numbers and check the solution using addition
• Use columns representing place value to subtract multiple-digit numbers

Subtract Whole Numbers

We know $7 - 3=4$ because $4+3=7$. Knowing all the addition number facts will help with subtraction. Then we can check subtraction by adding. In the examples above, our subtractions can be checked by addition.

 $7-3=4$ because $4+3=7$ $13-8=5$ because $5+8=13$ $43-26=17$ because $17+26=43$

Example

Subtract and then check by adding:

• $9 - 7$
• $8 - 3$

Solution

 1. $9 - 7$ Subtract 7 from 9. $2$ Check with addition. $2+7=9\quad\checkmark$
 2. $8 - 3$ Subtract 3 from 8. $5$ Check with addition. $5+3=8\quad\checkmark$

TRY IT

To subtract numbers with more than one digit, it is usually easier to write the numbers vertically in columns just as we did for addition. Align the digits by place value, and then subtract each column starting with the ones and then working to the left.

Example

Subtract and then check by adding: $89 - 61$.

TRY IT

When we modeled subtracting $26$ from $43$, we exchanged $1$ ten for $10$ ones. When we do this without the model, we say we borrow $1$ from the tens place and add $10$ to the ones place.

Find the difference of whole numbers

1. Write the numbers so each place value lines up vertically.
2. Subtract the digits in each place value. Work from right to left starting with the ones place. If the digit on top is less than the digit below, borrow as needed.
3. Continue subtracting each place value from right to left, borrowing if needed.

excercise

Subtract: $43 - 26$.

Example

Subtract and then check by adding: $207 - 64$.

try it

Subtract and then check by adding: $439 - 52$.

Subtract and then check by adding: $318 - 75$.

Example

Subtract and then check by adding: $910 - 586$.

Example

Subtract and then check by adding: $2,162 - 479$.

try it

Watch the video below to see another example of subtracting whole numbers by lining up place values.