1 and 19.
One.
19 and 2
1, 2, 19, 38.
1, 7, 19, 133.
Fifty-seven divided by three is 19, therefore three goes in evenly. If it goes in evenly, it is divisible.
1, 5, 19, and 95.
1, 7, 19, 133.
Each of these numbers goes evenly into 133: 1, 7, 19, 133.
1, 2, 4, 19, 38 and 76.
None, they're both prime numbers.
In this case, 1 is the only common multiple of 19 and 100 because 19 is odd and 100 is even.