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DS help

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Source: — Data Sufficiency |

Re: DS help

by Ian Stewart » Fri Jul 04, 2008 9:09 am
maria wrote:what is the value of the product DE?
1. ABCD> 0
2. BCDE = 0
Statement 1) isn't enough on its own- it doesn't even mention E.

From Statement 2) alone, we know the product of B, C, D and E is equal to zero. If a product is zero, one of the numbers in the product must be equal to zero. So we know that (at least) one of B, C, D and E is equal to zero. Still, we can't know which one. So 2) is not sufficient.

Together: From Statement 1), we know that none of A, B, C and D can be zero. If one of them was zero, the product would automatically be zero. Well, if B, C and D are not zero, but the product BCDE is zero, then E must be equal to zero. Thus DE = 0, and we have sufficient information.
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