What is the greatest common factor of 198 using prime factorization?

Answer 1

The greatest common factor (GCF) is often also called the greatest common divisor (GCD) or highest common factor (HCF). Keep in mind that these different terms all refer to the same thing: the largest integer which evenly divides two or more numbers.

Since 198 is a single number, you could say that it shares all of its factors with itself. So the greatest factor of 198 is 198.
You need at least two numbers to find a GCF.

Answer 2

First find all the factors of 252 and 198 by using prime factorization.

252 = 2 x 126 = 2 x 2 x 63 = 2 x 2 x 7 x 9 = 2 x 2 x 7 x 3 x 3

198 = 2 x 99 = 2 x 11 x 9 = 2 x 11 x 3 x 3

Then find all of the common factors of these

252 = 2 x 3 x 3 x 7 x 2

198 = 2 x 3 x 3 x 11

As you can see, both 252 and 198 have two 3s and one 2. If you multiply these together, you get:

2 x 3 x 3 = 18

18 is your answer

Answer 3

• Factors of 138: 1, 2, 3, 6, 23, 46, 69, 138
• Factors of 140: 1, 2, 4, 5, 7, 10, 14, 20, 28, 35, 70, 140
• Factors of 198: 1, 2, 3, 6, 9, 11, 18, 22, 33, 66, 99, 198
• GCF (138, 140, 198) = 2

Answer 4

You need at least two numbers to find a GCF.

Answer 5

1 x 198, 2 x 99, 3 x 66, 6 x 33, 9 x 22, 11 x 18.

Answer 6

198 and 396 have a GCF of 198.

Answer 7

The GCF is 33.

Answer 8

9 and 198