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GMATPrep2 problem- need shorter method

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by Ian Stewart » Mon Aug 25, 2008 1:51 pm
The numerator and denominator are both differences of squares:

1001^2 - 999^2 = (1001+999)(1001-999) = 2000*2
101^2 - 99^2 = (101+99)(101-99) = 200*2

Cancel (2000*2)/(200*2) to get 10.
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by jaydeer44 » Mon Aug 25, 2008 1:56 pm
thanks so much!
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