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Race Result Details |
| Racer | r (deroche1) |
| Race Number | 109 |
| Date | Wed, 18 Jan 2017 07:13:29 +0000 |
| Universe | michaelderoche |
| Speed |
100 WPM
 Try to beat?
|
| Accuracy | 95.2% |
| Rank | 1st place (out of 2) |
Text typed:
 
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Here 49^3=(48*49*50)+(1^2*49). We can solve 48*49 by the factoring method, but for this sort of problem, I prefer to use the close-together method. Using that method, we get 48*49=(50*47)+(1*2)=2352. Multiplying this by 50, we get 117,600, and therefore: 49^3=117,600+49=117,649.
— Secrets of Mental Math: The Mathemagician's Guide to Lightning Calculation and Amazing Math Tricks
 (book)
by Arthur Benjamin and Michael Shermer
(see stats)
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