Sunday, 11 August 2013

Fast Track Multiplication Techniques or Tricks

Trick 1
When a number (N) is multiplied by 9,99,999,… or (10n -1).
In such cases, number of zeros equal to number of 9s in (10n -1) are put extreme right of N to make a new number M and then N is subtracted from this new number to get the result. Clearly, (M - N) is the result of multiplication.

Example- Multiply 6243 with 999.

Solution. Here, N=6243, (10n 1)=(103 -1) = 999
According to the rule,
                                                (N)       (M)      (N)
                                    6243*999=6243000 - 6243
                        999 has three 9s and hence
                        Three zero are put at the right
                        End of N to make M.

N is subtracted from M
To get the result
Of multiplication.

Therefore- (M-N)=6236757

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