45, and all of its multiples
A number that is divisible by both 5 and 9 must be a multiple of their least common multiple (LCM). The LCM of 5 and 9 is 45. Therefore, any multiple of 45, such as 45, 90, or 135, will be divisible by both 5 and 9.
900
LCM(5, 9) = 45
As 9 is a multiple of 3, any multiple of 9 will do : 9,18,27,36,45,....
Which number is a factor of 10 , but not a multiple of 5
180
it would be 81 since it is a multiple of 9
18
18
36.
There are 5 multiples of 9. There are 4 multiples of 12. There is 1 number that is a multiple of both, 36.
7 & 9 only have one factor in common: 1. So the number which is a multiple of both is 7 x 9 = 63.