Question

The ten's digits of a two digit number is three times the unit digit. The sum of the number and the unit digit is $32$. Find the number.

• A. $21$
• B. $33$
• C. $43$
• D. $31$

Answer 1

The correct option is D $31$

Let the ones's digit $=x$

Therefore, tens's digit $=3x$

Original number $=10\left(3x\right)+x=31x$

Sum of number $+$ unit digit $=32$

$\Rightarrow 31x+x=32\Rightarrow x=1$

Tens digit will be $3x=3$.

Therefore, the number is $31$.