Rounding & Estimation

> Estimating Difference <

Estimating Difference

To estimate the difference , first round the
numbers. Then add. When estimating a
difference first decide what rounding will take
place.

Example word problem: Round to the nearest ten.

Kennedy saved up 624 pennies.  She wanted
some candy, so she use 339 of the pennies. 
About how many pennies does she have left.

Round to the nearest ten.

The actual difference is  624 - 339 = 285

Estimating sums