Estimate Products of Whole Numbers and Decimals

Estimate products of whole numbers and decimals by either rounding both factors or rounding the greatest factor

The estimate you get will depend on which numbers you round and to which place those numbers are rounded. Choose numbers that are easy to work with

For example, if we round both the factors in the expression 167 x 11, to the nearest ten, then we get: 170 x 10 = 1,700. If we were to round the greatest factor (167) to the nearest hundred (200), then we estimate the expression to be around: 200 x 11 = 2,200

In most cases, rounding both the factors is a better way of estimation, than just rounding the greatest factor, because the estimate is more close to the actual answer

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

You can use rounding and multiplication patterns to estimate sums. This is called clustering

When clustering, make sure that all the addends are close to the same, common number

For example, in the expression 64 + 58 + 61, all the numbers are close to 60. So, when estimating, 60 + 60 + 60 = 3 x 60 = 180