Estimate Sums and Differences of Whole Numbers and Decimals

Rounding is a way of adjusting numbers to make them simpler and easier to work with. Rounded numbers usually end with a zero

To round numbers using place values, identify the digit to the right of the digit to be rounded. If the digit is less than 5, round down. If the digit is 5 or greater, round up

To round dollars to the nearest dollar, look closely at the number of cents. If the number of cents is 50 or more, round up. If the number of cents is less than 50, round down

Round cents using place values

Sometimes an exact sum is needed. However, in some cases, only an approximate answer can solve our problem. We can estimate by finding an answer that is close to the exact answer

To estimate the sum of two numbers, round each number and add

When two numbers have different number of digits, it is best to round to the highest place of the smaller number

To round to the nearest dollar look at the ten cents. If ten cents value is 50 or greater than 50, we round to the next dollar. If ten cents value is less than 50, we round to that dollar

Sometimes an exact difference is needed. However, in some cases, only an approximate answer can solve our problem. We can estimate by finding an answer that is close to the exact answer

To estimate the difference two numbers, round each number and subtract

When two numbers have different number of digits, it is best to round to the highest place of the smaller number

To round to the nearest dollar look at the ten cents. If ten cents value is 50 or greater than 50, we round to the next dollar. If ten cents value is less than 50, we round to that dollar