Well, that's not the standard definition of "transfinite numbers". Anything that boils to 10x, where x is possibly stupidly large, has a trivially known number of digits - x. /grumblegrumblegrumble Incidentally, SunJumper's was an alternative way of writing the hyperoperation sequence, or superscripted Knuth's up-arrows. Starwhip's code I grant isn't much like mathematical notation. It may or may not terminate, but in any case can never make x larger than the maximum value of a double, which is something around 10308. If arbitrary-precision arithmetic was used it would not terminate and instead be equivalent to writing infinity, and thus banned. /wafflewafflewaffle 10PP, where P is that Poincare recurrence time. (Of the observable Universe, I assume.)