jsgf said: “interesting”

Claire said: “If you take two numbers that are two apart, and multiply them, it’s the same as if you square the number in the middle and subtract one.”

Me: “Really?”

Claire: “Yeah, like nine elevens is 99, which is one less than ten tens.”

Me: “Huh. Four sixes are 24, which is one less than five fives. Five sevens are 35. Six eights are 48. You might be onto something.”

I find paper and scribble:

n(n+2) = (n+1)^2 – 1
n^2 + 2n = n^2 + 2n + 1 – 1

Me: “How about that.”

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