 #### Question 1

Complete these additions and subtractions mentally.

a 12 + 12 = 12 + 13 = 25 − 12 = 25 + 25 = 50 − 26 = 19 + 19 = 99 + 99 = 51 + 51 = 51 + 52 = 120 + 130 = 190 + 190 =

#### Question 2

Rearrange these additions to make the mental calculation easier.

a 12 + 33 + 8 + 7 = 21 + 44 + 49 + 36 = 2 + 16 + 3 + 3 + 24 + 2 =

#### Question 3

Use the make up to ten strategy to calculate these.

a 28 + 26 = 19 + 34 = 97 + 46 =

#### Question 4

a 123 + 234 + 345 = 222 + 333 + 444 = 987 + 876 + 765 =

#### Question 5

Use the compensation method (add more than you need to one number, and then subtract the extra bit) to calculate these additions.

a 192 + 45 = 48 + 79 = 189 + 46 =

#### Question 6

Subtract a bit at a time to calculate these mentally.

a 224 − 22 = 444 − 36 = 1083 − 538 =

#### Question 7

Build up to the larger number and keep track of what is added to calculate the difference.

a 78 − 49 = 192 − 148 = 621 − 98 =

#### Question 8

Add the same to both numbers to calculate these subtractions.

a 87 − 64 = 290 − 43 = 444 − 96 =   