Because
there's no use for one Lego, unless you want to puncture someone's foot in the night by leaving it on a bedroom floor. Generally speaking there are loads of the little things- Legos. If there weren't you couldn't build anything.

And as for "maths"- you can keep your S on the end, along with all the extra "u"s you seem to need to sprinkle into words that are perfectly happy without them.
( The Resident Loon Not a demographic. Do not measure., Fri 2 May 2008, 12:49, Reply)