Solve subtraction calculations mentally by using known facts | Starter Quiz | Oak National Academy

In the following equation, which number is the subtrahend? 21 − 4 =17

• 21

• 4

• 7

Answer explanation

The subtrahend was 4 because this was the number that was subtracted from the minuend of 21 to find the a difference of 17

Solve the following calculation mentally by adjusting the minuend and subtrahend. 76 − 22 = (a)  

Answer explanation

22 − 2 = 20 and 76 − 2 = 74 so because of constant difference 76 − 22 = 74 − 20 = 54

Solve the following calculation using a mental strategy. (a)   = 150 − 68

Answer explanation

150 − 68 = 150 − 60 − 8 = 90 − 8 = 82

Solve the following calculation mentally by adjusting the subtrahend and then the difference. 165 − 27 = (a)  

Answer explanation

165 − 30 = 135 and 135 + 3 = 138

Solve the following calculation using a mental strategy. (a)   = 4,050 − 98

Answer explanation

4,050 − 100 = 3,950 so 4,050 − 98 = 3,952

Select the equivalent expressions (equal value) from the list below.

• 105 − 56

• 254 − 205

• 300 − 156

• 85 − 34

Answer explanation

105 − 56 = 49, 254 − 205 = 49 These expressions are equivalent because they are both equal to 49