GCF for 21 and 45

"Greatest Common Factor" Calculator

Greatest Common Factor of

and

What is the Greatest common Divisor of 21 and 45?

Answer: GCF of 21 and 45 is 3

(Three)

Finding GCF for 21 and 45 using all factors (divisors) listing

The first method to find GCF for numbers 21 and 45 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 45: 1, 3, 5, 9, 15, 45

So the Greatest Common Factor for 21 and 45 is 3

Finding GCF for 21 and 45 by Prime Factorization

The second method to find GCF for numbers 21 and 45 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 45: 3, 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 45

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 45? (The answer is: 3). Select the first number (e.g. '21') and the second number (e.g. '45'). 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
6453
7451
8451
9459
10455
11451
12453
13451
14451
154515
16451
17451
18459
19451
20455
21453
22451
23451
24453
25455
26451
27459
28451
29451
304515
31451
32451
33453
34451
35455

FAQ

What is the Greatest common Divisor of 21 and 45?

GCF of 21 and 45 is 3

See Also