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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!