GCF for 20 and 21

"Greatest Common Factor" Calculator

Greatest Common Factor of

and

What is the Greatest Common Divisor of 20 and 21?

Answer

GCF of 20 and 21 is 1

(One)

Finding GCF for 20 and 21 using all factors (divisors) listing

The first method to find GCF for numbers 20 and 21 is to list all factors for both numbers and pick the highest common one:

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

All factors of 21: 1, 3, 7, 21

So the Greatest Common Factor for 20 and 21 is 1

Finding GCF for 20 and 21 by Prime Factorization

The numbers 20 and 21 have no common prime factors, which means they are coprime (relatively prime). Therefore, GCF = 1.

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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 Divisor of 20 and 21? (The answer is: 1). Select the first number (e.g. '20') and the second number (e.g. '21'). 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.

"Greatest Common Factor" Calculator

Greatest Common Factor of

and

GCF Table

Number 1 Number 2 GCF
5 21 1
6 21 3
7 21 7
8 21 1
9 21 3
10 21 1
11 21 1
12 21 3
13 21 1
14 21 7
15 21 3
16 21 1
17 21 1
18 21 3
19 21 1
20 21 1
21 21 21
22 21 1
23 21 1
24 21 3
25 21 1
26 21 1
27 21 3
28 21 7
29 21 1
30 21 3
31 21 1
32 21 1
33 21 3
34 21 1

FAQ

What is the Greatest Common Divisor of 20 and 21?
GCF of 20 and 21 is 1

How to find the GCF of 20 and 21?
You can find the GCF of 20 and 21 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 20 and 21 is 1.

Are 20 and 21 coprime?
Yes, 20 and 21 are coprime (relatively prime) because their Greatest Common Factor is 1.

See Also