Greatest Common Factor of 20 and 285

GCF(20, 285) = 5, Greatest common factor of 20 and 285 is 5. Greatest Common Factor or Greatest Common Divisor of two numbers is the largest integer by which both the numbers can be divided. There are two different methods to calculate Greatest Common Factor of 20 and 285. Greatest Common Factor by prime factorization method and Greatest Common Factor by matching factors method.

Greatest Common Factor of 20 and 285 by prime factorization method

We will first find the prime factorization of 20 and 285.
Prime Factorization of 20 is 1, 2, 2, 5 and Prime Factorization of 285 is 1, 3, 5, 19.

  • Factorize\( (20) = \) \(1\times 2\times 2\times 5\)
  • Factorize\( (285) = \) \(1\times 3\times 5\times 19\)
Now we need to find any which are common for each number (1, 5) and multiply these numbers together.
\(GCF(20, 285) = 1\times 5 = 5\).

Greatest Common Factor of 20 and 285 by matching factors method

List of positive integers factors of 20 leaving a remainder zero is 1, 2, 4, 5, 10, 20
List of positive integers factors of 285 leaving a remainder zero is 1, 3, 5, 15, 19, 57, 95, 285
As you can see, 5 is the greatest and common number that 20 and 285 divides into.
So the greatest common factor 20 and 285 is 5.
\(GCF(20, 285) = 5\).

If you want to learn more about greatest common divisor, take a look at the Wikipedia page.
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