Question

In a two-digit number, the units digit is twice the ten's digit. If 27 is added to the number, the digits are reversed. Find the number.

• A. 52
• B. 36
• C. 40
• D. 28

Answer 1

The correct option is B

36

Let the digit in the units place be x and digit in the tens place be y.
According to first condition
$\Rightarrow$ x = 2y . . . . (1)
$\therefore$ the two digit number is 10y + x.
When 27 is added, the digits are reversed.[Given]
$\therefore$ 10y + x + 27 = 10x + y
$\Rightarrow 9x-9y=27$
$\Rightarrow x-y=3$ . . . . (2)
Putting x = 2y in equation (2), we get,
2y - y = 3 $\Rightarrow$ y = 3
Putting y = 3 in equation (2), we get,
x - 3 = 3 $\Rightarrow$ x = 6
10y + x = 10 $\times$ 3 + 6 = 36
Hence, the number is 36.