Estimating QuotientsUsing Compatible Numbers

Compatible Numbers

To find compatible numbers, look at the first two numbers in the dividend (the larger number in your division problem).

528 ÷ 7You want to find two numbers that are compatible with the number 7. A compatible number is CLOSE to 52, one bigger and one smaller than 52. It is also a multiple of 7.

Use division facts for 7 and patterns to find nearby compatible numbers for 528. The compatible numbers are MULTIPLES of 7, which make them easy to work with!

490 ÷ 7 = 70, 49 is smaller than 52

560 ÷ 7 = 80, 56 is larger than 52

The answer is between 70 and 80.

Compatible Numbers 71421283542495663707784

Multipl

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52

252 ÷ 3

Look at first two digits: 252The divisor is 3:

240 ÷ 3 = 80252 ÷ 3 =

270 ÷ 3 = 90

The best estimate is between 80 and 90.

369121518212427303336

25

368 ÷ 6

Look at first two digits: 368The divisor is 6:360 ÷ 6 = 60

The best estimate is 60.

**Sometimes there is only one compatible number.

3150 ÷ 9

Look at first two digits: 3150The divisor is 9:2700 ÷ 9 = 300

3150 ÷ 9 =3600 ÷ 9 = 400

The best estimate is between 80 and 90.

4000 ÷ 7

Look at first two digits: 4000The divisor is 7:3500 ÷ 7 = 500

4000 ÷ 7 =4200 ÷ 7 = 600

The best estimate is between 500 and 600.

440 ÷ 8

Look at first two digits: 440The divisor is 8:400 ÷ 8 = 50440 ÷ 8 =

480 ÷ 8 = 60

The best estimate is between 50 and 60.