A friend of mine asked me to write down any multidigit number. But, he put a condition, the

number should not end with a zero.

I put down the number 96452

Then he asked me to add up the five digits and subtract the total from the original number.

I did and here is what I got:

96452 – 26 = 96426

He then asked me to cross out any one of the five digits and tell him the remaining numbers. I

crossed out the 2 and told him the rest of the digits. I neither told him the original number nor

what I had done with it. Yet ‘pop’ he told me the exact number I had crossed out.

How did you explain it?

Dear Mohit,

The sum of digits of subtracted no. will be a multiple of 9 and not exactly 9.

the sum of digits of the subtracted no. is always 9, so, the omitted no. can be found out

When sum of digits is subtracted from any no. no. has to be multiple of 9. So, by adding the sum of remaining digits to the next nearest multiple of 9, it is easy to find out the number.