Question

The units digit of a two-digit number is 3 and seven times the sum of the digits is the number itself. Find the number.

Answer 1

Let tens digit = x

Units digit = 3

$\therefore$ Number = 3 + 10x

According to the condition,

7 (x + 3) = 3 + 10x

7x + 21 = 3 + 10x

21 - 3 = 10x - 7x $\Rightarrow$ 3x = 18

$x=\frac{18}{3}=6$

$\therefore$ Number = 3 + 10x

=3 + 10 $\times$ 6 = 3 + 60 = 63