GCF for 18 and 20

What is the Greatest Common Factor of 18 and 20?

Answer: GCF of 18 and 20 is 2

(Two)

Finding GCF for 18 and 20 using all factors (divisors) listing

The first method to find GCF for numbers 18 and 20 is to list all factors for both numbers and pick the highest common one:

All factors of 18: 1, 2, 3, 6, 9, 18

All factors of 20: 1, 2, 4, 5, 10, 20

So the Greatest Common Factor for 18 and 20 is 2

Finding GCF for 18 and 20 by Prime Factorization

The second method to find GCF for numbers 18 and 20 is to list all Prime Factors for both numbers and multiply the common ones:

All Prime Factors of 18: 2, 3, 3

All Prime Factors of 20: 2, 2, 5

As we can see there is only one Prime Factor common to both numbers. It is 2

So 2 is the Greatest Common Factor of 18 and 20

GCF Table

Number 1Number 2GCF
320
420
520
620
7201
820
920
1020
1120
1220
13201
1420
1520
1620
1720
1820
19201
202020
21201
22202
23201
24204
25205
26202
27201
28204
29201
302010
31201
32204

About "Greatest Common Factor" Calculator

This calculator will help you find the greatest common factor (GCF) of two numbers. For example, it can help you find out what is the Greatest Common Factor of 18 and 20? (The answer is: 2). Select the first number (e.g. '18') and the second number (e.g. '20'). After that hit the 'Calculate' button.
Greatest Common Factor (GCF) also known as the Greatest Common Divisor (GCD) or Highest Common Factor (HCF) - it is the largest positive integer that divides each of the integers with zero remainder

FAQ

What is the Greatest Common Factor of 18 and 20?

GCF of 18 and 20 is 2