Eight of them.
(60,2)(40,3)(30,4)(24,5)(20,6)
One pair: it's a prime number.
225 has five factor pairs:225,175,345,525,915,15
Two of them.
Three of them.
That's an infinite list unless you restrict it to factor pairs. The factor pairs of 120 are (120,1)(60,2)(40,3)(30,4)(24,5)(20,6)(15,8)(12,10)
Sixteen factor pairs.
The factor pairs of 120 are 1*120, 2*60, 3*40, 4*30, 5*24, 6*20, 8*15, and 10*12
(120,1)(60,2)(40,3)(30,4)(24,5)(20,6)(15,8)(12,10)
30 has four factor pairs:30,115,210,36,5
20 has 3 factor pairs. Pairs are (1,20), (2,10) and (9,9)
12 has 3 factor pairs and the pairs are (1,12), (2,6) and (3,4).
(60,2)(40,3)(30,4)(24,5)(20,6)
4/120, 8/60
76 has 3 factor pairs: (1,76), (2,38), (4,19).
One pair: it's a prime number.
"Dose" is a measured portion of a medicine. I am not aware of any factor pairs related to dose 18 or any other measured quantities of medication!18 does have 3 factor pairs.