DaphneV
Dec 10, 2016, 11:06 AM
So, this question comes in two parts:
Find the number of divisors of 189,720 that are (a) composite numbers, and (b) divisible by five.
I tried to solve the question by using a tree diagram, as I was shown in class.
(a)
189,720
4 x 47,430
6 x 7,605
15 x 37, 944
(Sorry if the diagram isn't as clear online, but it's shaped like a tree!)
Then, I did this:
(p+1)(q+1)(r+1)
= (4+1)(6+1)(15+1)
= 560 divisors
(b)
189,720
= 5 x 37,944
(p+1)(q+1)(r+1)
= (5+1)
= 6
I tried to follow the method we used in class, but I'd appreciate if someone could look over this and tell if it was right! Thank you!
Find the number of divisors of 189,720 that are (a) composite numbers, and (b) divisible by five.
I tried to solve the question by using a tree diagram, as I was shown in class.
(a)
189,720
4 x 47,430
6 x 7,605
15 x 37, 944
(Sorry if the diagram isn't as clear online, but it's shaped like a tree!)
Then, I did this:
(p+1)(q+1)(r+1)
= (4+1)(6+1)(15+1)
= 560 divisors
(b)
189,720
= 5 x 37,944
(p+1)(q+1)(r+1)
= (5+1)
= 6
I tried to follow the method we used in class, but I'd appreciate if someone could look over this and tell if it was right! Thank you!