Got something that's bugging you about maths? Post it below for a no-names-no-packdrill reply.

It doesn't matter how silly. If your one-times table is eluding you, give me a shout and we'll figure it out.

## Colin

Colin is a Weymouth maths tutor, author of several Maths For Dummies books and A-level maths guides. He started Flying Colours Maths in 2008.
He lives with an espresso pot and nothing to prove.

## Robert Anderson

It seems that Ramanujan said:

1 + 2 + 3 … = -1/12

For instance, it is mentioned in the play A Disappearing Number. It\’s mentioned here: http://bit.ly/SdZi0V and here http://bit.ly/RB7Yw2.

But that can\’t be right! What is he on about?

## Colin

Best question EVER.

In honesty, I have no idea, even after looking it up.

It seems like Euler came up with the same \’answer\’ a different way, using something called zeta function normalisation; Ramanujan came up with another method using the partial sums. I don\’t understand either of them, but might put some work into putting that right.

To the best of my gathering, both of the methods give a number that\’s not a sum in the normal sense, but a number that helps classify divergent series (ones which don\’t have a well-defined limit — like this one).

Some links that might help:

http://en.wikipedia.org/wiki/Ramanujan_summation

http://en.wikipedia.org/wiki/1_%2B_2_%2B_3_%2B_4_%2B_%E2%80%A6

http://en.wikipedia.org/wiki/Zeta_function_regularization

Thanks for the question — sorry I can\’t be more help!

## Robert Anderson

Watch this! http://youtu.be/w-I6XTVZXww

I’m even more baffled now because the ‘proof’ is not all that complicated…

## Colin

I’ve written a piece that explores the ‘traditional’ analysis of it (which says, of course, that it’s undefined) – going live tomorrow (January 15th).