How do u do this?

Question

What is the greatest common factor of 35,18?

Answer 1

1. List the prime factors of each number.
2. Multiply those factors both numbers have in common. If there are no common prime factors, the GCF is 1.

35 has factors of 5, 7
18 has 2, 3,3

By rule 2, the GCF is 1

Answer 2

One way to do it is to find all the prime factors of each of the two numbers, as other answerers have explained. However, when the numbers get large, this can get very difficult.

The other way uses the fact that if there is some number which goes into both numbers, then it must also go into the remainder from dividing one number by the other. Watch this with 3503 and 1891 :-

3503 / 1891 = 1 remainder 1612
1891 / 1612 = 1 remainder 279
1612 / 279 = 5 remainder 217
279 / 217 = 1 remainder 62
217 / 62 = 3 remainder 31
62 / 31 = 2 exactly, therefore GCF is 31.

You could get the answer this way while your classmates were still struggling to find the prime factors of either 3503 or 1891, so it is a useful method to know. For 35 and 18 it is pretty quick :-

35 / 18 = 1 remainder 17
18 / 17 = 1 remainder 1
17 / 1 = 17 exactly, therefore GCF is 1.

By the way, it is not usually called "greatest common factor". A longish time ago we called it "highest common factor", but the modern term is "greatest common divisor" or GCD for short.

Answer 3

Greatest Common Factor (GCF)
The greatest common factor of two or more whole numbers is the largest whole number that divides evenly into each of the numbers. There are two ways to find the greatest common factor. Remember to follow your homework instructions, if your teacher asks for a particular method.

The first method is to list all of the factors of each number, then list the common factors and choose the largest one.

Example: Find the GCF of 36 and 54.

The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, and 36.

The factors of 54 are 1, 2, 3, 6, 9, 18, 27, and 54.

The common factors of 36 and 54 are 1, 2, 3, 6, 9, 18

Although the numbers in bold are all common factors of both 36 and 54, 18 is the greatest common factor.

The second method is to list the prime factors, then multiply the common prime factors.

Example: Let's use the same numbers, 36 and 54.

The prime factorization of 36 is 2 x 2 x 3 x 3

The prime factorization of 54 is 2 x 3 x 3 x 3

Notice that the prime factorizations of 36 and 54 both have one 2 and two 3s in common. So, we simply multiply these common prime factors to find the greatest common factor. Like this...

2 x 3 x 3 = 18

Both methods work!

Answer 4

35= 7x5
18 = 2x3x3
so the greates common factor is 1
'

Answer 5

Prime factor both number