GCF for 18 and 28

What is the Greatest common Divisor of 18 and 28?

Answer: GCF of 18 and 28 is 2

(Two)

Finding GCF for 18 and 28 using all factors (divisors) listing

The first method to find GCF for numbers 18 and 28 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 28: 1, 2, 4, 7, 14, 28

So the Greatest Common Factor for 18 and 28 is 2

Finding GCF for 18 and 28 by Prime Factorization

The second method to find GCF for numbers 18 and 28 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 28: 2, 2, 7

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 28

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 18 and 28? (The answer is: 2). Select the first number (e.g. '18') and the second number (e.g. '28'). 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

GCF Table

Number 1Number 2GCF
3281
428
5281
6282
728
828
9281
1028
1128
1228
13281
1428
1528
1628
17281
1828
1928
2028
2128
22282
23281
2428
2528
26282
27281
282828
29281
30282
31281
32284

FAQ

What is the Greatest common Divisor of 18 and 28?

GCF of 18 and 28 is 2