Question

A two-digit number is such that the product of digit is 12. When 36 is added to the number the digits interchange their places. Determine the number.

Answer 1

Let the tens digit be then, the unit digits

Therefore, number

And number obtained by interchanging the digits

Then according to question

Or

So, the digit can never be negative.

Therefore,

When then the unit digits

.

And number

Thus, the required number be