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Multiplication Using Two Reference Numbers 93 Easy. Now let’s use 10 and 80 as reference numbers. +3 (10 × 8) 9 × 83 = 750 –1 3 ...
94 Speed Math for Kids Write them down and calculate the answers, and then see if you can do them all in your head. With practic ...
Multiplication Using Two Reference Numbers 95 (10 × 49) 9 × 486 = –1 –4 –49 We subtract 49 from 486. Is this diffi cult? Not at ...
96 Speed Math for Kids Here we have to multiply –6 by 3½. To do this, simply multiply 6 by 3, which is 18, then add half of 6, w ...
Multiplication Using Two Reference Numbers 97 (100 ÷ 2) 96 × 48 = 4,600 –4 –2 8 –2 4,608 Answer Th at worked out well, but what ...
98 Speed Math for Kids (100 ÷ 4) 97 × 23 = –3 –2 We divide 3 by 4 for an answer of ¾. Subtract ¾ from 23 (subtract 1 and give ba ...
Multiplication Using Two Reference Numbers 99 How about 7 × 26? I would say 20 times 7 is 140. To multiply by 20 we multiply by ...
100 Speed Math for Kids Now let’s try using reference numbers of 10 and 80. +3 (10 × 8) 13 × 76 = –4 Multiply 3 times 8 to get 2 ...
Multiplication Using Two Reference Numbers 101 Th irteen is 3 above 10, and 76 is 1 above 75. We multiply the 3 above the 13 by ...
102 Speed Math for Kids We multiply 4 by 3¼ to get 13 (4 × 3 = 12, plus a quarter of 4 gives another 1, making 13). Write 13 in ...
Multiplication Using Two Reference Numbers 103 Our work looks like this: (100 × 0.6) 98 × 58 = –2 –2 –1.2 Subtract 1.2 from 58 t ...
104 Speed Math for Kids multiply our answer of 64.2 by 100 to get 6,420. Multiplying the circled numbers, 4 times 3, gives us 12 ...
Multiplication Using Two Reference Numbers 105 (200 × 0.4) 189 × 77 = 7,260 –11 –3 14,520 –4.4 33 14,553 Answer It is interesti ...
= x 0 1 2 3 4 5 6 7 8 9 ( ) % < > + - = x 0 1 2 3 4 5 6 7 8 9 ( ) % < > + - = x 0 1 2 3 4 5 6 7 8 9 ( ) % < &g ...
Addition 107 What is the easy way to add 9? Add 10 and subtract 1. What is the easy way to add 8? Add 10 and subtract 2. What is ...
108 Speed Math for Kids Test you rself Tr y the se : a) 25 + 9 = b) 46 + 9 = c) 72 + 9 = d) 56 + 8 = e) 37 + 8 = f) 65 + 7 = The ...
Addition 109 And for d), you would say 424 plus 30 is 454, minus 2 is 452. Did you fi nd these easy to do in your head? What if ...
110 Speed Math for Kids Test you rself Try these problems in your head: a) 531 297 b) 333 249 c) 4,537 388 For a) you simply ad ...
Addition 111 Th is strategy makes it easy to keep track of your calculation and hold the numbers in your head. Order of addition ...
112 Speed Math for Kids plus 1. It is important that you can break up all numbers from 1 to 10 into their basic parts. 2 = 1 + 1 ...
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