Question

The sum of the digit of a two number is 15. If the digits of the given number are reversed, the number is

increased by the square of 3. The original number is ________

Answer 1

N = 10a + b
N' = 10b + a
a + b = 15
$N' = N+ {3}^{2}$
10b + a = 10a + b + 9
9b – 9a = 9
b – a = 1
a = 7, b = 8
N = 78.