GCF for 21 and 30

"Greatest Common Factor" Calculator

Greatest Common Factor of

and

What is the Greatest common Divisor of 21 and 30?

Answer: GCF of 21 and 30 is 3

(Three)

Finding GCF for 21 and 30 using all factors (divisors) listing

The first method to find GCF for numbers 21 and 30 is to list all factors for both numbers and pick the highest common one:

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

All factors of 30: 1, 2, 3, 5, 6, 10, 15, 30

So the Greatest Common Factor for 21 and 30 is 3

Finding GCF for 21 and 30 by Prime Factorization

The second method to find GCF for numbers 21 and 30 is to list all Prime Factors for both numbers and multiply the common ones:

All Prime Factors of 21: 3, 7

All Prime Factors of 30: 2, 3, 5

As we can see there is only one Prime Factor common to both numbers. It is 3

So 3 is the Greatest Common Factor of 21 and 30

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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 21 and 30? (The answer is: 3). Select the first number (e.g. '21') and the second number (e.g. '30'). 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 1Number 2GCF
6306
7301
8302
9303
103010
11301
12306
13301
14302
153015
16302
17301
18306
19301
203010
21303
22302
23301
24306
25305
26302
27303
28302
29301
303030
31301
32302
33303
34302
35305

FAQ

What is the Greatest common Divisor of 21 and 30?

GCF of 21 and 30 is 3

See Also