reply on: (999^2 - 1)/998 \ stacker news ~charts_and

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mhh, lol, I didn't think of calculating 999^2 in my head ... I thought there must be a trick somewhere.

doing it on scratch paper helps. I thought it was going to be a lot harder.

There is a trick.

Hint: remember the formula for (a^2 - b^2)...