July 12, 2012

MULTIPLYING A NUMBER BY 5


There are a lot of shortcuts and techniques in multiplying numbers, you just have to choose what is easy for you. This time, let us try to multiply numbers by 5. 

If a number is multiplied by 5, you could divide the number by 2 then multiply it by 10. This is easier because when a number is multiplied by 10, just simply append zero(0) to the number. This technique is very effective if the number being multiplied by 5 is divisible by 2.

The reason behind this technique is that 5 is the result when 10 is divided by 2 or 10/2 = 5. It means that if you multiply a number by 5, you can multiply it first by 10 then divide it by 2 or you can divide it by two then multiply by 10. The latter is easier. 

Let us use it in the following examples:

    




      The first thing to do is divide the number by 2. That is
      After that, multiply the result by 10 or simply append zero (0) on the result. That is
      Therefore, 


    



      Divide 186 by 2. 

     Multiply the result by 10.
    Therefore,

Now try these:
1. (56)(5)
2. (102)(5)
3. (258)(5)
4. (364)(5)
5. (273)(5)

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