The largest mathematically used number, so big that it is utterly inconceivable and in fact so vast that they must do a page of calculations to even get the last digit, is simply named 'Graham'.
As a way of trying to understand it's utter immensity the other large number they talk about in this programme is called a 'Goolge'. One 'Google' has more 0's after the 1 than there is atoms in our galaxy.
Should still be up on BBC Iplayer, a Horizon episode called 'Infinity', it will blow your insignificant minds...
