Digit Sum for SSC, Bank, Railways and CAT | Digital Sum- Killer Concept

Whether we are preparing for SSC, Bank PO, Railways, we generally get stuck in lengthy calculations which is very time-consuming, so here, we will see the method of Digital Sum which is very easy and convenient for speeding up our calculation. So let's check this out.




How to do:-

The digit-sum method can be used to check answers involving different arithmetic operations like multiplication, division, addition, subtraction, squares, square roots, cube roots. The procedure is very simple. We have to convert a given number into a single digit by repetitively adding up all the digits of that number till we get a single-digit number.

You have to keep on adding the numbers until you get a single-digit answer.

Rule Underlying in this method:-

We already know that a no. is divisible by 9 if the sum of the digits is divisible by 9.

So, in the digit sum method, we have the single-digit value of the total number which represents the remainder obtained on dividing that number by 9. And any number divisible by 9 leaves the remainder 0.

In the digital sum method, while we make a single-digit value in the process of adding all the nines and all the digits that add up to nine is completely divisible by 9, hence leaving the remainder 0.
Therefore, While calculating the digital sum of a number, you can eliminate all the nines and all the digits that add up to nine.
When you eliminate all the nine's and all the digits that add up to nine you will be able to calculate the digit sum of any number much faster. The elimination will have no effect on the final result.

So this was all about the Digital Sum, Hope you got an idea about Digital Sum.


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