The answer will depend on the problem!
Among other things, a knowledge about prime numbers and factoring can help you in finding least common multiples and greatest common factors.
It doesn't. You need common factors for that, not common multiples.
Least common multiples and lowest common denominators are essentially the same thing. Once the denominators are the same, it's easier to get the correct answer when adding and subtracting fractions.
The question makes no sense without some context. Finding the least common multiple will not help you, in any way, to write a history report or to ride a bike.
It can help by when finding the LCD (Least Common Denominator) you find the least number they have in common then that number is your equivalent fraction.
It will help when you are trying to add and subtract fractions.
Example: Find the LCM of 12 and 30.Write the multiples of 12: 12, 24, 36, 48, 60, 72, ...Write the multiples of 30: 30, 60, 90, ...The first number you find which is in both lists is the LCM: 60.
The least common factor of any set of numbers is 1, so that doesn't help at all. Finding the GCF of the numerator and denominator and dividing them by it will help to simplify a fraction. Finding the least common multiple of the denominators (called the least common denominator) will help when you add and subtract fractions. None of those are needed to multiply fractions.
The GCF helps in simplifying fractions and the LCM helps in adding and subtracting them.
6: 6, 12, 18, 24, 30, 36, 42, 48, 54, 60 20: 20, 40, 60 The LCM for 6 and 20 is 60. If you need help with finding the least common multiple (LCM) or greatest common factor (GCF) for some numbers then, on your computer, go to your search engine and type in "LCM calculator" to help you find the least common multiple or "GCF calculator" to help you find the greatest common factor.
Finding the GCF will help in simplifying fractions. Finding the LCM will help in adding and subtracting fractions.