Question

Tom used to workout every 6 days and Sam every 7 days. Tom and Sam both did workout together today. After how many minimum days will they both workout together?

• A. $21$
• B. $42$
• C. $36$
• D. $84$

Answer 1

The correct option is B $42$

Tom does workout every $6$ days.
Sam does workout every $7$ days.

If they workout together today, they will again workout on the day which is LCM of $6$ and $7$.

Prime factorisation of $6$ and $7$ will be
$6=2\times 3$
$7=7\times 1$
LCM will be $2\times 3\times 7=42$.
on ${42}^{th}$ day they will again workout together.