Question

In a 2-digit number, the digit at the unit's place is 5 less than the digit at the ten's place. The product of the digits is 36. Find the number. 

Answer 1

Let the digit in ten's place be x.

Then the one's place digit will be x − 5

The product of two digit = 36

x (x − 5) = 36

x² − 5x − 36 = 0

⇒ x² − 9x + 4x − 36 = 0

⇒ (x − 9) (x + 4) = 0

⇒ x = 9, −4

No. = 94