Answer:
2775
Step-by-step explanation:
Well of course since the problem is not restricted, the smallest number is 3. I'm almost sure that's not what you mean. The next smallest number is 2775. I found that using a programing language. I'm sure as well that does not satisfy the question, either.
I think you are intended to do this by finding the lowest common multiple and adding 3.
21: 3 * 7
28: 2 * 2 * 7
36: 2 * 2 * 3 * 3
44: 2 * 2 * 11
LCM = 2 * 2 * 3 * 3 * 7 * 11 = 2772
Now add 3 and the number you want is 2775
