Data Sufficiency

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.