Only the number 1.
16/9 = 17/9
3 and 1 will go into both number evenly leaving no remainders.
They both go into 1440, for example.
The number is 1.
16 and 9 are coprime so that the only number going into both is 1.
144
144
Only the number 1.
63
9 and 15 both go into 45. Example: 9,18,27,36,45 15,30,45
9 because both 9 and 3 go into the number
There's an infinite list of them. The smallest one is 144.
Any multiple of 63.
Sixty-three.
The LCM of both numbers is 720
6 and 9 both go into 54.