Question

Explain how to use estimation to help find the product of two decimals. Give an example with both estimated and actual answers.

Answer 1

Example: 2.56 × 3.16

Using estimation means rounding the two values to the most appropriate accuracy

For instance, we can round both values to the nearest whole number 
2.56 rounded to 3
3.16 rounded to 3

2.56 × 3.16 = 3 × 3 = 9

Or we can round both values to one decimal place
2.56 rounded to 2.6
3.16 rounded to 3.2

2.56 × 3.16 = 2.6 × 3.2 = 8.32

The actual answer of 2.56 × 3.16 = 8.0896 and the closest approximation is 8.32.

The more accurate the values are rounded, the closer it is to the actual value.