2-2 Mental Math: Using Compatible Numbers and Compensation

2-2 Mental Math: Using Compatible #s and Compensation Math Notes Mathematical Reasoning 1.0

Compatible Numbers Compatible numbers are numbers that are easy to compute mentally. 19 + 25 + 11 = 30 + 25 = 55

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

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

Guided Practice 9 + 1 + 25 = Any numbers you 9 + 1 = 10 can easily add FIRST to make this easier? 10 + 25 = __

Guided Practice 9 + 1 + 25 =

Guided Practice 9 + 1 + 25 = Any numbers you can easily add FIRST to make this easier?

Guided Practice 9 + 1 + 25 = Any numbers you 9 + 1 = 10 can easily add FIRST to make this easier?

Guided Practice 9 + 1 + 25 = Any numbers you 9 + 1 = 10 can easily add FIRST to make this easier? 35 10 + 25 = __

Guided Practice 7 + 13 + 19 =

Guided Practice 7 + 13 + 19 = Any numbers you can easily add FIRST to make this easier?

Guided Practice 7 + 13 + 19 = Any numbers you 7 + 13 = 20 can easily add FIRST to make this easier?

Guided Practice 7 + 13 + 19 = Any numbers you 7 + 13 = 20 can easily add FIRST to make this easier? 39 20 + 19 = __

Guided Practice 29 + 37 =

Guided Practice Remember, this is 29 + 37 = COMPENSATION with adding. ADD something, TAKE something away.

Guided Practice +1 Remember, this is 29 + 37 = COMPENSATION with adding. ADD something, TAKE something away.

Guided Practice +1 -1 Remember, this is 29 + 37 = COMPENSATION with adding. ADD something, TAKE something away.

Guided Practice +1 -1 Remember, this is 29 + 37 = COMPENSATION with adding. ADD something, TAKE something away. 30

Guided Practice +1 -1 Remember, this is 29 + 37 = COMPENSATION with adding. ADD something, TAKE something away. 30 36

Guided Practice +1 -1 Remember, this is 29 + 37 = COMPENSATION with adding. ADD something, TAKE something away. 30 36 30 + 36 = __

Guided Practice +1 -1 Remember, this is 29 + 37 = COMPENSATION with adding. ADD something, TAKE something away. 30 36 30 + 36 = 66 __

Guided Practice 67 + 14 =

Guided Practice Remember, this is 67 + 14 = COMPENSATION with adding. ADD something, TAKE something away.

Guided Practice +3 Remember, this is 67 + 14 = COMPENSATION with adding. ADD something, TAKE something away.

Guided Practice +3 -3 Remember, this is 67 + 14 = COMPENSATION with adding. ADD something, TAKE something away.

Guided Practice +3 -3 Remember, this is 67 + 14 = COMPENSATION with adding. ADD something, TAKE something away. 70

Guided Practice +3 -3 Remember, this is 67 + 14 = COMPENSATION with adding. ADD something, TAKE something away. 70 11

Guided Practice +3 -3 Remember, this is 67 + 14 = COMPENSATION with adding. ADD something, TAKE something away. 70 11 70 + 11 = __

Guided Practice +3 -3 Remember, this is 67 + 14 = COMPENSATION with adding. ADD something, TAKE something away. 70 11 81 70 + 11 = __

Guided Practice 38 - 19 =

Guided Practice Remember, this is 38 - 19 = COMPENSATION with subtracting. ADD something to BOTH numbers.

Guided Practice +2 Remember, this is 38 - 19 = COMPENSATION with subtracting. ADD something to BOTH numbers.

Guided Practice +2 +2 Remember, this is 38 - 19 = COMPENSATION with subtracting. ADD something to BOTH numbers.

Guided Practice +2 +2 Remember, this is 38 - 19 = COMPENSATION with subtracting. ADD something to BOTH numbers. 40

Guided Practice +2 +2 Remember, this is 38 - 19 = COMPENSATION with subtracting. ADD something to BOTH numbers. 40 21

Guided Practice +2 +2 Remember, this is 38 - 19 = COMPENSATION with subtracting. ADD something to BOTH numbers. 40 21 40 - 21 = __

Guided Practice +2 +2 Remember, this is 38 - 19 = COMPENSATION with subtracting. ADD something to BOTH numbers. 40 21 19 40 - 21 = __

Guided Practice 89 - 37 =

Guided Practice Remember, this is 89 - 37 = COMPENSATION with subtracting. ADD something to BOTH numbers.

Guided Practice -4 Remember, this is 89 - 37 = COMPENSATION with subtracting. ADD something to BOTH numbers.

Guided Practice -4 -4 Remember, this is 89 - 37 = COMPENSATION with subtracting. ADD something to BOTH numbers.

Guided Practice -4 -4 Remember, this is 89 - 37 = COMPENSATION with subtracting. ADD something to BOTH numbers. 85

Guided Practice -4 -4 Remember, this is 89 - 37 = COMPENSATION with subtracting. ADD something to BOTH numbers. 85 33

Guided Practice -4 -4 Remember, this is 89 - 37 = COMPENSATION with subtracting. ADD something to BOTH numbers. 85 33 85 - 33 = __

Guided Practice -4 -4 Remember, this is 89 - 37 = COMPENSATION with subtracting. ADD something to BOTH numbers. 85 33 85 - 33 = 52 __

2-2 Mental Math: Using Compatible Numbers and Compensation

by Rudy Alfonso on Aug 31, 2010

Accessibility

Tags

Upload Details

Usage Rights

1 Embed 4

Statistics

2-2 Mental Math: Using Compatible Numbers and Compensation — Presentation Transcript