GCF for 9 and 18

What is the Greatest common Divisor of 9 and 18?

Answer: GCF of 9 and 18 is 9

(Nine)

Finding GCF for 9 and 18 using all factors (divisors) listing

The first method to find GCF for numbers 9 and 18 is to list all factors for both numbers and pick the highest common one:

All factors of 9: 1, 3, 9

All factors of 18: 1, 2, 3, 6, 9, 18

So the Greatest Common Factor for 9 and 18 is 9

Finding GCF for 9 and 18 by Prime Factorization

The second method to find GCF for numbers 9 and 18 is to list all Prime Factors for both numbers and multiply the common ones:

All Prime Factors of 9: 3, 3

All Prime Factors of 18: 2, 3, 3

As we can see there are Prime Factors common to both numbers: 3, 3

Now we need to multiply them to find GCF: 3 × 3 = 9

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 9 and 18? (The answer is: 9). Select the first number (e.g. '9') and the second number (e.g. '18'). 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
1181
218
318
418
518
618
718
818
918
1018
1118
1218
1318
1418
1518
1618
1718
181818
19181
20182
21183
22182
23181
2418
25181
26182
27189
28182
29181
30186

FAQ

What is the Greatest common Divisor of 9 and 18?

GCF of 9 and 18 is 9