Question

Arun is instructed to clap every time the count of the instructor reaches a multiple of 3. Varun is instructed to clap every time the count reaches a multiple of 7. They would clap at the same time when the count reaches ___

• A. Multiples of 4
• B. Multiples of 10
• C. Multiples of 21
• D. They can never clap at the same time

Answer 1

The correct option is C Multiples of 21

For Arun and Varun to clap together, the count has to be a multiple of both 3 and 7.
LCM of 3 and 7 which is 21.
So, they will clap together every time the count reaches a multiple of 21.