Subject: General Aptitude · Chapter: Problems on Numbers · Exam: 2003 · Marks: · Difficulty:
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
Answer (as printed): C
Explanation
Let the ten's digit be $x$. Then, number $=10 x+3$ and sum of digits $=(x+3)$. So, $(x+3)=\frac{1}{7}(10 x+3) \Leftrightarrow 7 x+21$ $$=10 x+3 \Leftrightarrow 3 x=18 \Leftrightarrow x=6 .$$ Hence, the number is 63.
Explanation as extracted from the printed page; notation may be imperfect.