You may also like

Consecutive Numbers

An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

Calendar Capers

Choose any three by three square of dates on a calendar page...

Days and Dates

Investigate how you can work out what day of the week your birthday will be on next year, and the year after...

Tricky Customer

Age 11 to 14 Short
Challenge Level

Charlie wants to buy a new house but he doesn't like house numbers that are divisible by $3$ or by $5$.

If all the houses numbered between $100$ and $150$ inclusive are for sale, how many houses can he choose from?

If you liked this problem, here is an NRICH task that challenges you to use similar mathematical ideas.

This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.