It is 126, as in the question.
126/420 = 3/10 in its lowest terms
126 over 147 in lowest terms is 6/7
90/126 is 5/7 in its lowest terms
1/19
54/126 is 3/7 in lowest term. This means that the LCM (Lowest Common Multiple) is 18.
The lowest common multiple of 21 and 126 is 126.
126/2394 = 1/19 by dividing by 126
It is in its lowest terms.
The lowest common multiple of 126 and 105 is 630.
126
126
504