Lesson: Working with Powers of Ten

Comment on Working with Powers of Ten

In the last example you divided 6.31 / 10^6. Is this essentially the same thing as multiplying 6.31 X 10^-6? Scientific Notation? Thanks!
-Yvonne
gmat-admin's picture

Yes - precisely.

Brent,

I have a doubt on the exercise 393 from the O.G. (2017 edition). Could you explain me in a different answer from the OG Answer Explanations, please?

Thank you in advance.
gmat-admin's picture

Sure thing.
Here's my step-by-step solution: https://gmatclub.com/forum/are-all-of-the-numbers-in-a-certain-list-of-1...

If you have any questions about my solution, don't hesitate to ask.

Cheers,
Brent

Brent,

Sorry, but I can't see that the Statement 2 is sufficient, why the sum of 3 numbers must be equal? Couldn't I put 3+4+5=12?

Cheers,
Pedro
gmat-admin's picture

You're right about 3 + 4 + 5 = 12, but with that example, we're only dealing with three numbers (and we're told that the list has 15 numbers).

At this point, even if we want to add just one more number to the list, we can see that we end up having problems satisfying the condition that "the sum of ANY 3 numbers in the list is 12".

For example, what happens if we add another 3 to the list to get {3, 3, 4, 5}?

At this point, we cannot say that the sum of ANY 3 numbers in the list is 12. For example, if we choose 3, 3, and 5, the sum of those 3 numbers is NOT 12.

Does that help?

Cheers,
Brent

Aha! Now it is clear for me!

Thank you very much!

Cheers,
Pedro

Hi Brent,
Do you have a solution for this question https://gmatclub.com/forum/if-z-is-a-three-digit-positive-integer-what-is-the-value-of-69999.html
I am having a hard time coming up with a method of how to come up with values z=230, z=221, hence cannot fully understand proposed solutions
gmat-admin's picture

Nice question!
Here's my full solution: https://gmatclub.com/forum/if-z-is-a-three-digit-positive-integer-what-i...

Cheers,
Brent

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