Mental Math Strategy: Compensation in Subtraction

This video tutorial introduces the mental math strategy of compensation, focusing on subtraction. It explains how to reformulate subtraction problems to make them easier to solve mentally. The video provides three examples: 46 - 19, 76 - 37, and 91 - 42, demonstrating how to adjust the subtrahend and minuend to create equivalent differences that are simpler to compute.

What is the main focus of the compensation strategy discussed in the video?

• Addition

• Multiplication

• Division

• Subtraction

In the first example, what number is added to both the subtrahend and minuend to simplify the subtraction?

• 2

• 4

• 1

• 3

What is the equivalent subtraction problem for 46 - 19 using compensation?

• 46 - 20

• 46 - 18

• 47 - 19

• 47 - 20

In the second example, how much is added to the subtrahend 37 to make it a friendly number?

• 5

• 4

• 3

• 2

What is the equivalent subtraction problem for 76 - 37 using compensation?

• 79 - 40

• 76 - 37

• 76 - 40

• 79 - 37

In the third example, what adjustment is made to the subtrahend 42 to simplify the subtraction?

• Subtract 3

• Add 3

• Subtract 2

• Add 2

What is the equivalent subtraction problem for 91 - 42 using compensation?

• 89 - 40

• 89 - 42

• 91 - 42

• 91 - 40

What is the final result of the subtraction 91 - 42 using the compensation method?

• 49

• 45

• 47

• 51