523 * 489 using mental math 523 * 500 = 52300 + 52300 + 52300 + 52300 = 11 less groups... sounds complicated. Any other ideas? Thanks, Terminator
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We may use the identity ( x+a)(x+b) = x^2 + x(a+b) + ab Let x = 500, a=23 b = -11 and proceed
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