That's an infinite list.
15, 30, 45, 60, 75, 90 and so on.
Any multiple of 15.
Which number is a factor of 10 , but not a multiple of 5
255
2,4,6,7,8,9,10,11,12,13,14,16,17,18,19,20........
15
30 is the smallest number that is a multiple of both 6 and 15
Such a number does not exist. 3600 is 60 squared and 4900 is 70 squared There is no number between 60 and 70 that is a multiple of 15 so there can be no square between 3600 and 4900 that is a multiple of 15.
15, 30, 45
15
It is 105
The number 20 is.
It is not possible to give a sensible answer to this question. The least common multiple (LCM) refers to a multiple that is COMMON to two or more numbers. You have only one number in the question!