3-8Example 2

Find the difference of 9,642 and 2,157. Use expanded form.

1. What is the greatest place value of the numbers?

thousands

3-8Example 2

Find the difference of 9,642 and 2,157. Use expanded form.

2. Round the numbers to the greatest place value.

10,000 and 2,000

3-8Example 2

Find the difference of 9,642 and 2,157. Use expanded form.

3. Write the estimate.

10,000 – 2,000 = 8,000

3-8Example 2

Find the difference of 9,642 and 2,157. Use expanded form.

4. Write the numbers in expanded form.

9,000 + 600 + 40 + 2− (2,000 + 100 + 50 + 7)

3-8Example 2

Find the difference of 9,642 and 2,157. Use expanded form.

5. Notice that 50 > 40 and 7 > 2.

9,000 + 600 + 30 + 12− (2,000 + 100 + 50 + 7)

Regroup tens to ones.

9,000 + 500 + 130 + 12− (2,000 + 100 + 50 + 7)

Regroup hundreds to tens.

3-8Example 2

Find the difference of 9,642 and 2,157. Use expanded form.

6. Subtract the columns and write the difference in standard form.

9,000 + 500 + 130 + 12− (2,000 + 100 + 50 + 7)

7,000 + 400 + 80 + 5

7,000 + 400 + 80 + 5 = 7,485

3-8Example 2

Find the difference of 9,642 and 2,157. Use expanded form.

7. Compare your answer and estimate. 7,485 is close to 8,000 so it is reasonable.