Martin had 7 pounds of grapes left, and he gave away 2

5
of them. Explain how to use compatible numbers to estimate the amount of grapes he gave away.

1 answer

To estimate the amount of grapes Martin gave away using compatible numbers, you can first round the numbers to make the calculation easier. In this case, we'll round the 7 pounds of grapes to a compatible number that's easier to work with.

  1. Identify the original number of grapes: Martin has 7 pounds of grapes.

  2. Determine the fraction he gave away: Martin gave away \( \frac{2}{5} \) of his grapes.

  3. Use compatible numbers to estimate: Instead of using 7 directly, we can round it to a nearby number that is easier to work with, like 10.

  4. Calculate \( \frac{2}{5} \) of this rounded number:

    • Find \( \frac{2}{5} \) of 10:
    • \( \frac{2}{5} \) of 10 = 4.

Thus, using the compatible number of 10, we estimate that Martin gave away about 4 pounds of grapes.

This method of rounding to compatible numbers helps simplify the calculation while still providing a reasonable estimate of the amount given away.