Question

The units digit of a two digit no. is twice its tens digit. When the digits are reversed, the no. is increased by 27. Find the original number

Answer 1

Let the digits be x and y

Then the two-digit number is 10x + y

Given : y = 2x ----------1

Now 27 added to the no

10x + y + 27 = 10y + x

9y – 9x = 27

y – x = 3 -----------2

Substitute the value of y in eqn 2

2x – x = 3

x = 3

and y = 2 * 3 = 6

Therefore the no is 10x + y = 10 * 3 + 6 = 36

Answer : The two digit no is 36.