Any job where you need to add or subtract fractions.
You can't do the LCM of 400 because you need two numbers to do the LCM of, for example, the LCM of 12 and 8 would be 24.
You would use it when adding fractions.
You need at least two numbers to find an LCM no matter what you use.
When you are adding or subtracting fractions.
When you are adding and subtracting fractions.
It doesn't matter which method you use. You still need at least two numbers to find an LCM. There is no LCM of 20.
No matter what method you use, you need at least two numbers to find an LCM.
Avoidance. It is impossible to find the LCM of a single number. You need at least two.
To add and subtract unlike fractions.
If I was trying to find a least common multiple, I would use multiplication.