1.
2-2 Mental Math:
Using Compatible
#s and Compensation
Math Notes
Mathematical Reasoning 1.0
2.
Compatible Numbers
Compatible numbers are numbers that
are easy to compute mentally.
19 + 25 + 11 = 30 + 25
= 55
3.
Compensation Numbers
Compensation involves deciding which number to
adjust to make it easier to add or subtract.
Compensate by changing the other number.
47 + 16
Add 3 Subtract 3
to adjust
50 + 13 = 63
4.
Compensation Numbers
Compensation involves deciding which number to
adjust to make it easier to add or subtract.
Compensate by changing the other number.
73 - 38
Add 2
Add 2
to adjust
75 - 40 = 35
5.
Guided Practice
9 + 1 + 25 =
Any numbers you
9 + 1 = 10 can easily add
FIRST to make this
easier?
10 + 25 = __
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