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Objective: To be able to use mental methods of calculation.

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Presentation on theme: "Objective: To be able to use mental methods of calculation."— Presentation transcript:

1 Objective: To be able to use mental methods of calculation

2 Add and subtract small numbers – – – – 1 – 4 7 – – – – – – 2 – 1 13 – – 3 – 4 =43 =15 =6 =13 =12 =7

3 Add and subtract multiples of – – – – – – – – – – 10 =140 =30 =50 =70 =110 =30 =60

4 Pairs of 2-digit numbers = = 134

5 Pairs of 2-digit numbers 76 – 58 – 876 – 50 26– 8 = – 58 – 5076 – 8 68– 50 = 18

6 Pairs of 2-digit numbers – – =105 =60 =92 =91 =63 =43 =133 =46

7 Partitioning = 491

8 Partitioning and more 14.3 – =

9 Work out these: – – – – 8.5 =191 =322 =11.3 =125 =18 =49 =3.7 =3.9

10 Compensating = 7.6

11 Compensating = 236

12 Work out these: – – – – 7.8 =274 =195 =12.6 =107 =47 =18 =2.4 =24.6

13 Find the perimeter of these shapes ANSWERS:

14 Multiplication and Division Mental Methods

15 Use factors 3.2 x x 10 = x 3 = ÷ ÷ 3 = ÷ 2 = = 10 x 3 6 = 3 x 2 so ÷6 is ÷3÷2

16 Work out these: 2.2 x x x ÷ ÷ ÷ 18 =2.2 x10 x3 = 66 =5.2 x10 x4 = 208 =6.1 x6 x2=36.6 x2=73.2 =189 ÷9 ÷10=21 ÷10=2.1 =350 ÷7 ÷2 = 50 ÷2 = 25 =666 ÷6 ÷3 = 111 ÷3=37

17 Double and Halve 6 x 4.5 = 3 x 9 halve one number, double the other = x 7.5 = 6 x 15 halve one number, double the other = 3 x 30 halve one number, double the other = 90

18 Work out these: 30 x x x = 15 x 5 = 75 = 24 x 2.5 = 12 x 5 = 60 = 32 x 0.25 =16 x 0.5 =8 x 1 = 8

19 Choose from 1, 2, 3, 4, 5 (use each number no more than once each) a) □ - □ + □ = 5 b) □ + □ - □ = 4 c) □ x □ - □ = 3 d) (□ + □) ÷ □ = 2 e) (□ + □) ÷ (□ + □) =

20 Use each of 1, 2, 4, 6, 8, 12 once each so that the product of the number on each side of the triangle is x 8 x 6 = 48 4 x 2 x 6 = 48 4 x 12 x 1 = 48


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