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Objective: To be able to use mental methods of calculation. Pairs of 2-digit numbers. 76 + 58. 76 + 58. 70 + 50. + 6 + 8. 76 + 8. + 50. 120. + 14. 84. + 50. 120 + 10 + 4. = 134. = 134. Pairs of 2-digit numbers. 76 – 58. 76 – 58. 76 – 50. – 8. 76 – 8. – 50. 26. – 8.
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Pairs of 2-digit numbers 76 + 58 76 + 58 70 + 50 + 6 + 8 76 + 8 + 50 120 + 14 84 + 50 120 + 10 + 4 = 134 = 134
Pairs of 2-digit numbers 76 – 58 76 – 58 76 – 50 – 8 76 – 8 – 50 26 – 8 68 –50 = 18 = 18
Partitioning 426 + 65 = 491 +60 +5 426 486 491
Partitioning and more 14.3 – 5.5 = 8.8 -0.2 -0.3 -5 8.8 9.0 9.3 14.3
Compensating 4.7 + 2.9 = 7.6 +3 -0.1 4.7 7.6 7.7
Compensating 530 - 294 = 236 -300 +6 230 236 530
3.3 3.3 5.4 5.4 4.2 4.2 6.9 4.9 3.7 2.2 2.2 2.2 2.2 3.7 Find the perimeter of these shapes ANSWERS: 19.9 17.7 16.2
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) (□ + □) ÷ (□ + □) = 1 4 1 2 5 1 2 4 2 5 1 3 2 4 1 3 2
1 12 8 4 6 2 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 48 4 x 12 x 1 = 48 1 x 8 x 6 = 48 4 x 2 x 6 = 48