Two and two is four,
But three and three is nine;
Four and four is eighty,
But five and five is none.
What is the next line in the sequence?
multiples of the squares of the numbers. (2x2x1, 3x3x1, 4x4x5, 5x5x0)
So the question becomes
what case does 6 fall under
I'll go with
the cases are the square mod 5, since the squares, and five, are involved anyway. The three cases correspond to -1, +1, and 0 mod 5. So 2^2 and 3^2 are both negative, and 5^2 is zero, while 4^2 and 6^2 are both positive.
six and six is one hundred and eighty.