Mental Math

01

(1)

48 + 135=

(2)

17 + 67=

(3)

8 X 198=

(4)

57 – 32=

(5)

122 ÷ 4=

(6)

16 X 15 =

(7)

32 X 25 =

(8)

57+88=

(9)

84 x 6 =

(10)

432 ÷6=

endReturn to Beginning

solutions

(1)48 + 135=

Think50 + 133=183

Compensation

(1)

48 + 135=Think

50 + 135=185185-2 = 183Compensation

(2)

17 + 77 =

Think10 + 77 = 87; 87 + 7 = 94

Break up and Bridge

(3) 8 x 98=Think

8 x 100 = 800800 – (2 x 8) = 784Compensation

(4)

57 – 32=Think

55 – 30= 25Balance for a

Constant Difference

(5)122 ÷ 4=Think

122 ÷ 2 ÷ 2 61 ÷ 2 = 30.5

(6)

16 X 15 =Think

8 X 30 =240Halving and Doubling

(7)32 X 25 = Think

8 X 4 X 25 = 8 x100 = 800

Compatible Factors

(8) 57+88=Think

= 50 + 80 = 130 and 7 + 8 = 15=130 + 15=145

Front End Addition

(9) 84 x 6 =Think

80 x 6 = 4804 x 6 = 24480 + 24 = 504

Front End Multiplication

(10) 432 ÷6=Think

(420 + 12)÷6 =70+2 = 72

Partition the Dividend