Question

a number has two digits whose sum is 9,if 27 is added to number ,its digits get interchanged.find the number

Answer 1

Answer:

27 is divisible by 9. All numbers whose digits sum to 9, or to a set of digits which sum to 9, are divisible by 9. So we know that our number is divisible by 9 and that the new sum will also be divisible by 9.

Let’s try 18. 18 plus 27 is not 81, so that’s no good… but it gives us a clue.

We’re going to need a pair closer to the center, and yet not at the center. It can’t be 9*5, because 45 and 54 are only 9 apart.

But it can be 9*4. 36 is 9 less than 45 which we just saw is 9 less than 54 and that is 9 less than 63. 3*9=27, so 36 is 27 less than 63, it’s interchanged digits counterpart.

Answer 2

Answer:

Correct answer - 36

3 + 6 = 9

36 + 27 = 63