Question

Question 99

Solve the following:

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

Answer 1

Let ten's digit of two-digit number be x.
Then, unit's digit =2x
$\therefore Number10\times x+2x=10x+2x=12x$
On reversing the digits,
$NewNumber=10\times \left(2x\right)+x=20x+x=21x$
According to the question,
12x+27=21x
$\Rightarrow 21x-12x=27\Rightarrow 9x=27\Rightarrow x=3$
Hence, the required number is $12\times 3,$ i.e. 36.