MENTAL MULTIPLICATION (3)

How to multiply two numbers with same tens and above digits and unit digits add to 10.

Hi folks, this time we are going to learn how we can mentally multiply two numbers with same tens and above digits and whose unit digit sums to 10. Believe me this trick can do wonders in some of the most difficult calculations.

Like 33X37 (7+3=10 and same tens digit 3)

This can be done as

33X37=(3X4)(7X3)

=1221

Simply multiply the tens digits and multiply the tens digit with the next number to it.

43X47=(4X5)(3X7) (7+3=10 and same tens digit 4)

=2021

Simple but effective technique isn't it?

Now Do these MENTALLY (Select Between <<>> to see the answer):

22X28= <<616>>

34X36= <<1224>>

71X79= <<5609>>

68X62= <<4216>>

132X138= <<18216>>

496X494= <<245024>>

729X721= <<525609>>

How can it help in CAT,GMAT,GRE,SAT etc.

There might not be a direct question asked but this trick comes handy in data interpretation questions.

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Thats it folks, catch you next time, until then if you have any query regarding anything contact me at friggere.Sumit@gmail.com