Question

Use compatible numbers to estimate the quotient. 5,590 divided by 72

Answer 1

Since

7 * 8 = 56

a good place to start could be

70 * 80 = 5,600

Then

72 * 80 = (70 + 2) * 80 = (70 * 80) + (2 * 80)

= 5,600 + 160 = 5,760

This number is larger than 5,590, so let's pick another factor smaller than 80 by subtracting away as many 72s as we need:

5,760 - 72 = 5,688 = 72 * 79

5,688 - 72 = 5,616 = 72 * 78

5,616 - 72 = 5,544 = 72 * 77

So the quotient is 77, and we have

5,590 = (72 * 77) + 46