Tricks for fast calculation by 5
It is a simple trick which is very intuitive and easy to understand. Many QuickerMaths.com followers might find it very simple. However, there are many who will enjoy this simple yet readily usable trick to multiply any number by five.
1. Multiplying 5 times an even number: halve the number you are multiplying by and place a zero after the number.
i. 5 * 136, half of 136 is 68, add a zero for an answer of 680.
ii. 5 * 874, half of 874 is 437; add a zero for an answer of 4370.
2. Multiplying 5 times an odd number: subtract one from the number you are multiplying, then halve that number and place a 5 after the resulting number.
i. 343 * 5 =
Subtract 1 from 343 and half the result = 171. Right hand side will always by 5. Hence the answer is 1715
or, (343-1)/2 | 5 = 1715 .
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