Irish Math

Q: In what town lives the mathematician who can only multiply by two?
A: Dublin.

Prime Weed

Q: What do prime numbers and stoners have in common?
A: The higher they are, the more spaced out they get.

Noah Multiply

After the flood, Noah tells the animals from the Arc to "go forth and multiply."
After a few months, Noah figures he better wander around and see how the animals are doing. Everybody is happy until he comes across a couple of snakes - they are quite downcast and not very happy. Noah asks what wrong, and they say "We are Adders, so we can't multiply!"
Noah rubs his chin for a few moments, and then goes into the forest, cuts down a couple of trees, and makes a table out of them.
Then he puts the snakes up on the platform he has made, and says "Now you should be happy. Everybody knows that adders can multiply with log tables!"