Basic Math Examples

$640 - 540$

Step 1

Round $640$ to $650$ .

$650 - 540$

Step 2

Round $- 540$ to $- 550$ .

$650 - 550$

Step 3

Subtract $550$ from $650$ .

$100$

Step 4

The approximate value of $640 - 540$ found by front end estimation.

$640 - 540 \approx 100$