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geeta (chief accountant)     23 April 2011

Multiply Up to 20X20 In Your Head

 

In just FIVE minutes you should learn to quickly multiply up to 20x20 in your head.
 With this trick, you will be able to multiply any two numbers from 11 to 19 in your head quickly, without the use of a calculator.

I will assume that you know your multiplication table reasonably well up to 10x10.

Try this:

    * Take 15 x 13 for an example.
    * Always place the larger number of the two on top in your mind.
    * Then draw the shape of Africa mentally so it covers the 15 and the 3 from the 13 below. Those covered numbers are all you need.
    * First add 15 + 3 = 18
    * Add a zero behind it (multiply by 10) to get 180.
    * Multiply the covered lower 3 x the single digit above it the "5" (3x5= 15)
    * Add 180 + 15 = 195. 



Learning

 5 Replies


(Guest)

YES, VERY GOOD SYSTEM OF  CALCULATIONS.KEEP IT UP.GOOD LUCK.

N.K.Assumi (Advocate)     23 April 2011

Nice and interesting.

Ravikant Soni (LAWYER IN JAIPUR)     23 April 2011

wow it works!!!!!!!!!!

is there any formulae for three and succesive digits??

Tarun Dhingra (Advocate)     07 May 2011

 

IT IS SO HELPFULL .. THANKS ... 

Gaurav Gulati (CA)     22 September 2012

Gr8,,it really works

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