3.5 Estimating Quotients
I can estimate quotients
Notes
 Remember that the purpose of estimation is to be able to do
the work (IN YOUR HEAD)
 Use compatible numbers to estimate division
o Rounding for estimating division is not the same as
regular rounding – you must use compatible #’s
o If you can’t mentally, you have not rounded correctly
 Always ask: What multiple of (divisor)is close to (first 2 digits of
dividend)? (your bffed)
 Round the dividend so that it is a multiple of the divisor
 Solve the math fact, and bring extra zeros to the answer
Examples
Estimate 4,126 ÷ 8.
Estimate 23,078 ÷ 4.
Estimate 462,028 ÷ 7.
Think: 40 is close to 41 and is
a multiple of 8.
Think: 24 is close to 23 and is
a multiple of 4.
Think: 49 is close to 46 and is a
multiple of 7.
4,126  8

4,000  8 = 500
23,078  4
 
24,000  4 = 6,000
462,028  7

490,000  7 = 70,000
So, 4,126  8 is about
500
So, 23,078  4 is about
6,000
So, 462,028  7 is about
70,000
Example A: you would
normally round this to
4,000 and that is OK
since 40 is compatible
with 8.
Example B: you would
normally round this
number to 23,000, but
that is not compatible
with 4. You round it to
24,000 because 24 is
compatible with 4.
Example C: you would
normally round this to
500,000 or 460,000,
but neither of those is
compatible with 7. So,
you round it to
490,000 because 49 is
compatible with 7.
Examples: choose compatible numbers (use your bffed)
1)
635 ÷ 8 becomes ______ ÷ 8 = _______
What multiple of 8 is closest to 63?
2)
374 ÷ 9 becomes ______ ÷ 9 = _______
What multiple of 9 is closest to 37?
3)
3,357 ÷ 4 becomes ______ ÷ 4 = _______
What multiple of 4 is closest to 33?
4)
6,628 ÷ 7 becomes ______ ÷ 7 = ________
What multiple of 7 is closest to 66?
5)
44,113 ÷ 6 becomes _________ ÷ 6 = __________
What multiple of 6 is closest to 44?
Samples: Estimate each of the following problems (show rounding)
1)
473 ÷ 6 = ________________
2)
572 ÷ 9 = ________________
3)
8,392 ÷ 7 = ________________
4)
22,568 ÷ 3 = _________________
5)
356, 980 ÷ 8 = ______________________
6)
1,934,877 ÷ 4 = _________________________________