AI Tutor - Lucy
Multiplication and division connect to speed, growth, and measurement. In 11 Plus Maths, they reveal how numbers behave in patterns, sequences, and real-world applications.
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To divide a number by 50: divide by 100, then multiply by 2:
1,275 ÷ 50 = (1,275 ÷ 100) x 2 = 12.75 x 2 = 25.5
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To multiply a number by 90: first multiply the number by 10, then subtract the original number from it, and finally multiply your answer by 10:
17 × 90 = ((17 x 10) - 17) x 10 = (170 - 17) x 10 = 153 x 10 = 1,530 |
To multiply a number by 12, first multiply the number by 10, then add twice the original number to it:
406 × 12 = (406 x 10) + (406 x 2) = 4,060 + 812 = 4,872 |
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To multiply a number by 800, multiply the number by 2, then by 2 again, and again by 2, and finally by 100:
24 × 800 = (24 x 2 x 2 x 2) x 100 = (48 x 2 x 2) x 100 = (96 x 2) x 100 = 192 x 100 = 19,200 |
To multiply a number by 50: first divide by 2, then move the digits 2 places to the left:
138 × 50 = (138÷ 2) x 100 = 69 x 100. Move the d.p. 2 places to the right gives 6,900 |
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To multiply a number by 25: multiply by 100, then divide by 4:
16.5 × 25 = (16.5 x 100) ÷ 4 = 1,650 ÷ 4 = 412.5 |
To multiply a number by 110, first multiply by 100, then multiply by 10 and just add your two answers together:
34 x 110 = (34 x 100) + (34 x 10) = 3,400 = 340 = 3,740 |
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To divide a number by 5: first multiply by 2 and then move the digits to the right:
14.72 ÷ 5 = (14.72 × 2) ÷ 10 = 29.44 ÷ 10 . Move the d.p. 1 place to the left gives 2.944 |
To multiply a number by 13, first multiply the number by 10, then multiply it by 3 and finally, add your two answers together:
18 x 13 = (18 x 10) + (18 x 3) = 180 + 54 = 234 |
3,846 ÷ 2 = 1,923 ÷ 100 = 19.23