Calculating Square of numbers quickly...

Lets calculate the square of 54

So (54)^2 = 5^2 +4 -- 4^2 = 25 +4 ----16 =29-------16= 2916

 (55)^2 = 5^2 +5 --5^2=25+5------25=30---------25= 3025

 (56)^2 = 5^2 + 6--6^2=25+6------36= 31--------36= 3136 etc..

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Multiply any large number by 12 mentally in seconds

To multiply any number by 12 just double last digit and thereafter double each digit and add it to its neighbour

For example 21314 * 12 = 255768

Lets break it into simple steps:

Step 1: 021314 * 12 = _____8 (Double of Last Digit 4= 8 )

Step 2: 021314 * 12 = ____68 (Now Double 1= 2, and add it to 4, 2+4=6)

Step 3: 021314 * 12= ___768 (Now Double 3=6, and add it to 1, 6+1=7)

Step 4: 021314 * 12= __5768 (Now Double 1=2, and add it to 3, 2+3=5)

Step 5: 021314 * 12= _55768 (Now Double 2=4, and add it to 1, 4+1=5)

Step 6: 021314 * 12= 255768 (Now Double 0=0, and add it to 2, 0+2=2)

So your final answer of 21314 * 12 = 255768

Is 456138 divisible by 9?

Now, it only takes 2 seconds for you to determine the answer.

No let see the solution

To test whether a certain large number is divisible by 9 or not,'just add all the digits of the number and if the end result is divisible by 9,then you can say that the entire large number will be divisible by 9 too'.

4+5+6+1+3+8=27

Now since 27 is divisible by 9 so 456138 will be divisible by 9 too.

43*11

To multiply 43 and 11,imagine there is a space between 43

43*11= 4_3 (Put an imaginary space in between)

Now,what to do with that space?

Just add 4 and 3 and put the result in the imaginary space

So, 43 * 11 =473 (which is your answer)

Isn't it great?

Lets try some more examples:

1) 35 * 11 = 3 (3+5) 5 = 385

2) 81 * 11 = 8 (8+1) 1 = 891

3) 72 * 11 = 7 (7+2) 2 = 792 etc..