There cannot be any such thing as a "highest common multiple". Once you find the least common multiple of a set of numbers, you can keep adding the LCM to itself over and over again. Each new number you get will be a common multiple of your set of numbers, but each new number will always be larger than the previous. This means that you can keep adding while the number approaches infinity and you will still never find a highest multiple.
The Least Common Multiple (LCM) for 21 63 is 63
The least common multiple of 27 and 63 is 189.
Since 63 is a multiple of 9, it is automatically the LCM of this problem.
The Least Common Multiple of 21, 63, 147: 441
The Least Common Multiple of 9, 7, and 3 is 63.
The Least Common Multiple (LCM) for 49 63 21 is 441.
The Least Common Multiple (LCM) for 63 70 is 630.
The least common multiple of the numbers 190 and 63 is 11,970.
The least common multiple of the numbers 47 and 63 is 2,961.
The least common multiple of the numbers 48 and 63 is 1,008.
Least common multiple of 63 and 56 is 504.
The Least Common Multiple (LCM) for 49 63 is 441.