The 'Cheryl's Birthday' maths test for the top 15/16 year olds in Singapore - can you solve it?
Here is a link to the problem that's taken the world by storm and a video on how to solve it.
For the 'What colour hat am I wearing' puzzle - click here.
Two students arrange to meet - both thought they had arrived at the correct time, but one was 29 minutes late - how come? Click here.
Want some more? Click here.