My son sent me the following problem which I have since discovered has been doing the rounds on the Internet.

I cannot find the original source – thank you whoever originally posed the problem!

**This problem can be solved by pre-school children in five to ten minutes, by programmers in an hour and by people in higher education ….well, check it yourself!**

I’m pleased to say despite my various Maths degrees I solved the problem quickly!

I obviously have the mind of a pre-schooler!

You can find a hint then check the answer **here**.

I present the problem as posed everywhere – though it looks like a misuse of the = sign!

The problem reminded me of some fun sequences to try with your students!

Get them thinking outside that box!

Try these ….

2, 3, 3, 5, 10, 13, 39, 43, 172, 177, …

2, 12, 1112, 3112, 132112, 1113122112, ….

For the answers and several more puzzles see **Puzzle Sequences** from the Online Encyclopedia of Integer Sequences.

See also this post on **Sequences** for further resources.

More **puzzles resources**.