Why do this problem?
is a useful one when children are being introduced to, or continuing work, on multiples (and factors). It could be illustrated practically with real chairs and children holding numbered cards.
Can you think of a good way to record this?
How about using counters numbered $1$ to $30$ or writing $1$ to $30$ on bits of paper and arranging them?
Can you think of a link to factors and multiples which may help?
Is $6$ a factor of $30$? Is $4$ a factor of $30$?
Learners could try with other numbers besides $6$ and $4$. If they find these problems straightforward they could try this problem
about multiples and other sets of numbers.
Many children will find it helpful to draw out the six chairs and use numbered counters (or numbered bits of paper) to find out what happens. Encourage quick recording before the bits of paper get blown away!