Answer:
Explanation:
For smaller numbers you can simply look at the factors or multiples for each number and find the greatest common multiple of them.
For 18, 24, and 30 those factors look like this:
Factors for 18: 1, 2, 3, 6, 9, and 18
Factors for 24: 1, 2, 3, 4, 6, 8, 12, and 24
Factors for 30: 1, 2, 3, 5, 6, 10, 15, and 30
As you can see when you list out the factors of each number, 6 is the greatest number that 18, 24, and 30 divides into.
Prime Factors
As the numbers get larger, or you want to compare multiple numbers at the same time to find the GCF, you can see how listing out all of the factors would become too much. To fix this, you can use prime factors.
List out all of the prime factors for each number:
Prime Factors for 18: 2, 3, and 3
Prime Factors for 24: 2, 2, 2, and 3
Prime Factors for 30: 2, 3, and 5
Now that we have the list of prime factors, we need to find any which are common for each number.
Looking at the occurences of common prime factors in 18, 24, and 30 we can see that the commonly occuring prime factors are 2 and 3.
To calculate the prime factor, we multiply these numbers together:
HCF = 2 x 3 = 6