Question

In a number between 9 and 100,the product of the digits is 20 and their sum is 9.​

Answer 1

It will be 45 and 54.

Explanation:

First, the number is between 9 and 100, so this number have 2 digits.

Call the number is ab. (a#0)

We have their sum is 9, means: a+b=9 (1)

Can find a lot of results: 18, 27, 36, 45, 54, 63, 72, 81

Now, try to eliminate some results...

The product of the digits is 20, means: ab=20 (2)

So we just choose 45 and 54 because it's suitable with (1) and (2).