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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.
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doing it on scratch paper helps. I thought it was going to be a lot harder.
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There is a trick.
Hint: remember the formula for (a^2 - b^2)...
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(999^2)=998001 998001-1=998000 998000/998=1000 =1000