# Estimating a Difference of Whole Numbers

The whole numbers are first rounded as specified, i.e., rounded to the nearest ten, hundred and so on. Then the difference of the rounded whole numbers is found to **estimate** the difference of whole numbers.

Estimate the difference 6,57󠄀3 − 4,536 by first rounding each number to the nearest hundred.

### Solution

**Step 1:**

In 6,573, the tens digit, 7 is greater than 5. So we round up 6,573 to the nearest hundred as 6,600.

**Step 2:**

In 4,536, the tens digit, 3 is less than 5. So we round down 4,536 to nearest hundred as 4,500.

**Step 3:**

So the estimated difference is 6,600 − 4,500 = 2,100.

Estimate the difference 44,904 − 23,091 by first rounding each number to the nearest thousand.

### Solution

**Step 1:**

In 44,904, the hundreds digit, 9 is greater than 5. So we round up 44,904 to the nearest thousand 45,000.

**Step 2:**

In 23,091, the hundreds digit, 0 is less than 5. So we round down 23,091 to nearest thousand 23,000.

**Step 3:**

So the estimated difference is 45,000 − 23,000 = 22,000