Eight of the very hardest maths puzzles we could find

In the past month, the world has been gripped by a series of maths and logic puzzles that were originally set for children.

First came the parked car puzzle which was set as a test for primary school children in Hong Kong but many adults still found tricky to solve. Then came Cheryl's birthday, set for 15 to 16-year-olds in Singapore but seemingly impossible for anyone to solve. And finally this week came the rod and string conundrum which stumped 96 per cent of top maths students in the US when it first appeared back in the 1990s.

Because all have proved so popular, and many of you seem to have already solved the original three, we've pored through the records to find eight more puzzles to leave you chewing your pencil and pulling out your hair.

Let us know how you get on...

1. How to beat Roger Federer at Wimbledon

Thanks to a set of temporary magical powers you are in the final of the Wimbledon tennis championships up against seven-time winner Roger Federer. Your powers cannot last for the whole match and you must therefore choose the optimum time for them to run out. What is the score that gives you the maximum chance of winning?

Question via Peter Winkler.

Solution can be found here.

2. Get the olive out of the Martini glass

You must rearrange these matchsticks so that the olive (that's the thing in the middle) is removed from the Martini glass. The olive must not be touched and you are only allowed to move two of the matchsticks. The Martini glass can be turned onto its left or right side, or even upside down, but must remain in the exact same shape.

None of the below images are the solution because the olive is still inside the glass or because the glass has taken a different form.

Puzzle via Scientific American.

Solution can be found here.

3. Draw one line on this equation to make it correct

Puzzle via Sourish Jana.

Solution can be found here.

4. 1,000 school lockers

There is a school with 1,000 students and 1,000 lockers. On the first day of term the headteacher asks the first student to go along and open every single locker, he asks the second to go to every second locker and close it, the third to go to every third locker and close it if it is open or open it if it is closed, the fourth to go to the fourth locker and so on. The process is completed with the thousandth student. How many lockers are open at the end?

Question via Pzzls.com.

Solution can be found here.

5. Crazy cut

Add one cut (or draw one line), which doesn't need to be straight, that can divide this shape into two identical parts.

Puzzle via Scientific American.

Solution can be found here.

6. Coloured socks puzzle

You are getting dressed in the dark and realise that you forgot to bind all your socks together into pairs. However you know there are exactly 10 pairs of white socks and 10 pairs of black socks in your draw. All the socks are exactly the same except for their colour. How many socks do you need to take with you to ensure you have at least a pair that match?

Puzzle via the Guardian.

Solution can be found here.

7. Rays through the squares

Can you prove that angle C is the sum of angles A and B?

Puzzle via the Puzzles.com.

One solution can be found here. Another can be found in this video.

8. Love in Kleptopia

John and Mary have fallen in love. John wants to send Mary a ring through the post but in their country of Kleptopia, any package that is not locked will have its contents stolen. John and Mary have plenty of padlocks but neither has the other's key. How can John get the ring safely to Mary?

Puzzle via Peter Winkler.

Solution can be found here.

How many did you get right? Are there any great maths puzzles we've left out? Let us know in the comments below...

More: Only 4 per cent of top students could answer this maths problem. Can you?