The document discusses two mental math strategies: compatible numbers and compensation. Compatible numbers are those that are easy to add mentally, like numbers near multiples of 10. Compensation involves adjusting one number up or down to make the calculation easier, such as adding 3 to one number and subtracting 3 from the other. Examples demonstrate using these strategies to mentally calculate additions and subtractions.
15. 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
16. 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
17. 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
18. 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
19. 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 +
20. 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 =
21. 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
27. 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
to adjust
28. 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
29. 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
30. 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
31. 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 -
32. 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 -
33. 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 =
34. 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
70. Guided Practice
Remember, this is
COMPENSATION
89 - 37 = with subtracting.
ADD (or SUBTRACT)
something to BOTH
numbers.
71. Guided Practice
Remember, this is
-4
COMPENSATION
89 - 37 = with subtracting.
ADD (or SUBTRACT)
something to BOTH
numbers.
72. Guided Practice
Remember, this is
-4 -4
COMPENSATION
89 - 37 = with subtracting.
ADD (or SUBTRACT)
something to BOTH
numbers.
73. Guided Practice
Remember, this is
-4 -4
COMPENSATION
89 - 37 = with subtracting.
ADD (or SUBTRACT)
something to BOTH
numbers.
85
74. Guided Practice
Remember, this is
-4 -4
COMPENSATION
89 - 37 = with subtracting.
ADD (or SUBTRACT)
something to BOTH
numbers.
85 33
75. Guided Practice
Remember, this is
-4 -4
COMPENSATION
89 - 37 = with subtracting.
ADD (or SUBTRACT)
something to BOTH
numbers.
85 33
85 - 33 = __
76. Guided Practice
Remember, this is
-4 -4
COMPENSATION
89 - 37 = with subtracting.
ADD (or SUBTRACT)
something to BOTH
numbers.
85 33
85 - 33 = 52
__