What is the lowest common multiple of 4 6 and 7?

Answer 1

The Lowest Common Multiple (LCM) of a series of numbers must be formed by using the prime factors of each number - but if any of the factors are shared between two or more numbers they need only be used once

The prime factors of 4 are 2 and 2. So the LCM will need to have 2 and 2 as factors

The prime factors of 6 are 2 and 3. As there is a 2 already in the list, we need only add a 3. Now the LCM must have 2, 2 and 3.

The number 7 is prime, so it needs to be added to the list also. Now we have 2, 2, 3 and 7 - this gives us 84.