Question

Martin had 7 pounds of grapes left and gave away 2/5 of them explain how to use comparable numbers to estimate the amount of grapes he gave away

Answer 1

Find a number close to Two-fifths that can be mentally multiplied by 7.

A number close to Two-fifths is One-half.

Multiply 7 by One-half.

The estimate is 3.5 pounds.

Explanation:

Answer 2

See below

Explanation:

Compatible numbers are numbers that are easy to use in mental arithmetic.

Martin gave away ⅖ of 7 lb of grapes, so the amount he gave away was

⅖ × 7 lb

⅖ is close to ²/₄ (½), and it is easy to take half of something mentally.

Half of 7 is about 3, so Martin gave away about 3 lb of grapes (the exact answer is 2.8 lb).