Tough Puzzles & Brain Teasers
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02 Feb 2019

# Can Anyone give the trick for this ?

For example : 25*10=250.

10 i.e., any value say x will be constant.If number other than 10,20,...

The other two numbers which will be taken has same number of digits as (2+5=7) and (2+5+0=7).

2mos ago

I am totally at a loss. What exactly is being said?

If you are talking about the sum of the digits in the numbers being multiplied and the same for the answer product, the rules concerning the digit sums apply.

Digit sum of a number is the sum of the digits of the number. If the sum exceeds one digit, the operation is repeated till a single digit results.

E.G. : Digit sum of 258 = 2+5+8=15=1+5=6

1. Sum of the Digit sums of addends (numbers being added) equals digit sum of the sum of the numbers.

E.G.: 258 + 14 = 272

Sum of the Digit sum of addends = 6+5=11=1+1=2

Digit sum of the sum= 2+7+2=11=1+1=2

So, Sum of Digit sums equals Digit sum of the sum

2. Product of the Digit sums of factors equals the digit sum of the product.

I am sure this can be worked on the lines of above by anyone.