Question

A number of two digits has $3$ for its unit's digit, and the sum of digits is $\frac{1}{7}$ of the number itself. The number is

• A. $43$
• B. $53$
• C. $63$
• D. $73$

Answer 1

Answer: (C)

$63$

Let the number be $10x+y$

$\Rightarrow$ unit's digit = y; ten's = x

$\Rightarrow y=3$

and $x+y=\frac{1}{7}(10x+y)$

$\Rightarrow 7x+7y=10x+y$

$\Rightarrow 3x=6y\Rightarrow x=2y=2.3$

$\Rightarrow x=6$

$\Rightarrow$ Number $=63\Rightarrow \left(C\right)$