Moderate Number System Solved QuestionAptitude Discussion

 Q. The least common multiple of two natural numbers $a$ and $b$, is 399. What is the minimum possible sum of the digits of the number a(given $a > b$)?
 ✖ A. 1 ✔ B. 3 ✖ C. 5 ✖ D. 7

Solution:
Option(B) is correct

Factorize $399 = 3×7×19$
The possible pairs are: $(57,7), (21,19), (399,1), (133,3)$

The least possible sum is given when $a =21 \text{ and }b =19$
And the sum is $2+1 =3$