Let p be a two-digit number and q be the number consisting of same digits written in reverse order. If p x q = 2430, then what is the difference between p and q?

The given product p × q = 2430 …(i)

The last digit is 0, so one two of the digits must be 5 and other one an even number 2, 4, 6 or 8.

Let this unknown digit be x.
So, p = 10x + 5 and q = 50 + x
putting in (i), (10x + 5) × (50 + x) = 2430

Now, try 2, 4, 6 and 8, x = 4

Therefore, p = 45 and q = 54
Required difference = q – p = 54 – 45 = 9