Hi mevicks,

On DS questions, I'm always curious about WHY the numbers/words are what they are. GMAT questions are written by humans to test other humans, so there's likely to be a pattern/formula/rule that is "built in" to the question (and there's usually more than 1).

Here, I'm curious abou the 6.038; THAT'S a real specific number. WHY did the author choose THAT number????

Before going to the Facts, I'm going to make some quick notes about the info that we're given:

If Z = 1, then Y = 60.38
If Z = 2, then Y = 603.8
If Z = 3, then Y = 6038
If Z = 4, then Y = 60,380
If Z = 5, then Y = 603,800

Fact 1 tells us that 6500 < Y < 65,000

The ONLY possibility is Z = 4
Fact 1 is SUFFICIENT

Fact 2 tells us that 10^4 < Y < 10^5
So 10,000 < Y < 100,000

The ONLY possibility is Z = 4
Fact 2 is SUFFICIENT

Final Answer: D

GMAT assassins aren't born, they're made,
Rich

Just another note about patterns... whenever you see 10 taken to an exponent, like 10^x, they're testing place value (or you can call it Scientific Notation, powers of 10, orders of magnitude, etc).

When we want to know the value of z in 10^z, we really want to know: "6.038 will be raised to what power of 10," or in other words "where will the decimal go?"

1) If y is in a range that's one order of magnitude 6,500->65,000, there can only be one value in there that's 6.038 raised to some power of ten (some specific order of magnitude). Sufficient.

2) Again, y is in a range that's a different of one order of magnitude. Again, sufficient.