GCF for 18 and 15
"Greatest Common Factor" Calculator
What is the Greatest common Divisor of 18 and 15?
Answer: GCF of 18 and 15 is 3
(Three)
Finding GCF for 18 and 15 using all factors (divisors) listing
The first method to find GCF for numbers 18 and 15 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 15: 1, 3, 5, 15
So the Greatest Common Factor for 18 and 15 is 3
Finding GCF for 18 and 15 by Prime Factorization
The second method to find GCF for numbers 18 and 15 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 15: 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 18 and 15
Related Calculations
See Also
- Least Common Multiple - Find the Least Common Multiple (LCM) of two numbers
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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 15? (The answer is: 3). Select the first number (e.g. '18') and the second number (e.g. '15'). 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