There is none because the Least Common Denominator (or LCD) is the Least Common Multiple (LCM) of the denominators of two or more fractions.
The answer to all questions! 42.
84
It is: 42
84
84/14 = 6 84/7 = 12 84/3 = 28 Hence 84 is the least common denominator
7 x 6 x 5 = 210
42
126
84
84
It is: 42
The least common denominator of 6,7, and 8 is the least common multiple of those numbers. This is 168.
1008
420
It is 630
126
42
84