Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

So i have a silly question. Once we break 90 down into its prime factors of 2,3,3,5, how do we know how many divisors of 90 this gives us ?

Not silly at all. I don't know how many people know this, but remember this method and remember it well...

To find the number of divisors (or factors):
1) Prime factorize
2) Add 1 to the power of the factors
3) Multiply them together to get answer

For example, 90 = 2^1 * 3^2 * 5^1
So the powers are 1, 2, 1
Then add 1 to the powers and you get: 1+1=2, 2+1=3, 1+1=2
Then multiply them together: 2*3*2 = 12
So 12 is the the number of divisors (or factors) that 90 has

If you are in doubt, try it with any number...there is a theory behind this method, but I'm not going into that.

So i have a silly question. Once we break 90 down into its prime factors of 2,3,3,5, how do we know how many divisors of 90 this gives us ?

Not silly at all. I don't know how many people know this, but remember this method and remember it well...

To find the number of divisors: 1) Prime factorize 2) Add 1 to the power of the factors 3) Multiply them together to get answer

For example, 90 = 2^1 * 3^2 * 5^1 So the powers are 1, 2, 1 Then add 1 to the powers and you get: 1+1=2, 2+1=3, 1+1=2 Then multiply then together: 2*3*2 = 12 So 12 is the the number of divisors (or factors) that 90 has

well explained bkk.. you had explained this in a much earlier post that i was able to pick up, so now the concept is nice and clear to me and i can easily apply this, thanks!

I couldn’t help myself but stay impressed. young leader who can now basically speak Chinese and handle things alone (I’m Korean Canadian by the way, so...