GCF for 15 and 40

What is the Greatest common Divisor of 15 and 40?

Answer: GCF of 15 and 40 is 5

(Five)

Finding GCF for 15 and 40 using all factors (divisors) listing

The first method to find GCF for numbers 15 and 40 is to list all factors for both numbers and pick the highest common one:

All factors of 15: 1, 3, 5, 15

All factors of 40: 1, 2, 4, 5, 8, 10, 20, 40

So the Greatest Common Factor for 15 and 40 is 5

Finding GCF for 15 and 40 by Prime Factorization

The second method to find GCF for numbers 15 and 40 is to list all Prime Factors for both numbers and multiply the common ones:

All Prime Factors of 15: 3, 5

All Prime Factors of 40: 2, 2, 2, 5

As we can see there is only one Prime Factor common to both numbers. It is 5

So 5 is the Greatest Common Factor of 15 and 40

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 15 and 40? (The answer is: 5). Select the first number (e.g. '15') and the second number (e.g. '40'). 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
1401
2402
3401
440
540
6402
7401
840
940
1040
11401
1240
13401
14402
1540
1640
17401
1840
19401
2040
2140
22402
23401
2440
2540
26402
27401
2840
29401
3040

FAQ

What is the Greatest common Divisor of 15 and 40?

GCF of 15 and 40 is 5