**This is incredible.**

Cast your mind back to maths class at school. Chances are you found the subject a little tedious.

But numbers can be exciting. At least they can when appearing to conjure some sort of mysterious witchcraft.

This 'maths trick' has been around a little while, but cropped up on Twitter on Friday and dumbfounded some people.

The formula works out your shoe size and age in six simple steps - to begin, the method requires only your shoe size, and then guides you through the process to magic up the your age.

It worked for us, but there's a distinct caveat - the whole thing only works if you've not yet had your birthday. But it's early 2016, so it should work for most of you.

**Here goes:**

Mind blown. Take your shoe size. Times by 5. Add 50. Times by 20. Add 1015. Subtract yr you were born. Answer = your shoe size and your age.

— Lucy Tobin (@lucytobin) January 15, 2016

**Others reacted in a similar fashion.**

@lucytobin WHAT how did that just happen

— Kate Leaver (@kateileaver) January 15, 2016

@ES_JoBourke @lucytobin what is this new witchcraft?

— Peter Campbell (@Petercampbell1) January 15, 2016

If you want a relatively simple solution and explanation, there's one here. It's algebra - there's method to the mathsness.

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