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?
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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.