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Dividing by 5

Mastering the doubling operation will enable us to divide by 5 easily. This technique is well discussed in Chapter 9 of our best-selling book “25 Math Short Cuts” Since 5 is equal to 10/2, dividing by 5 is the same…

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Multiplication by 5

Most of us, especially those who know only the conventional right to left method of multiplication would pick choice a: 132,231 x 5. This is because the multiplier is composed of small digits. But if you have read our Math…

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Dividing a number by 2 is also called halving. This is a very important skill that all students should develop early. Halving can be used also in dividing by 4 and by 8 and also in multiplying by 5, 25…

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Casting out 9s

When I published my book “Algebra Made Easy as Arithmetic”, Ms. Encarnacion Reyes, long time president of the San Pablo City chapter of the Mathematics Teachers Association of the Philippines commented: “I’m so glad that you included the casting out…

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