GCF for 21 and 51

"Greatest Common Factor" Calculator

Greatest Common Factor of

and

What is the Greatest common Divisor of 21 and 51?

Answer: GCF of 21 and 51 is 3

(Three)

Finding GCF for 21 and 51 using all factors (divisors) listing

The first method to find GCF for numbers 21 and 51 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 51: 1, 3, 17, 51

So the Greatest Common Factor for 21 and 51 is 3

Finding GCF for 21 and 51 by Prime Factorization

The second method to find GCF for numbers 21 and 51 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 51: 3, 17

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 51

Related Calculations

See Also

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 51? (The answer is: 3). Select the first number (e.g. '21') and the second number (e.g. '51'). 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
6513
7511
8511
9513
10511
11511
12513
13511
14511
15513
16511
175117
18513
19511
20511
21513
22511
23511
24513
25511
26511
27513
28511
29511
30513
31511
32511
33513
345117
35511

FAQ

What is the Greatest common Divisor of 21 and 51?

GCF of 21 and 51 is 3

See Also