Question

If a number multiple of both $3$ and $5$, then the number is multiple of

• A. $12$
• B. $13$
• C. $14$
• D. $15$

Answer 1

The correct option is D $15$

If a number is multiple of both $3$ and $5$, then the number is multiple of $15$.
Example: $315$
Here $3+1+5=9$ is multiple of $3$, so $315$ is divisible by $3$.
The number ends with $5$, so $315$ is divisible by $5$.
Therefore, $315$ is divisible by $15$.