Created By : Jatin Gogia
Reviewed By : Rajasekhar Valipishetty
Last Updated : Apr 06, 2023
Make use of GCF Calculator to quickly find the Greatest Common Factor of numbers 21, 27 i.e. 3 largest integer by which both the numbers can be divided.
Greatest common factor (GCF) of 21 and 27 is 3.
GCF(21,27) = 3
Greatest common factor or Greatest common divisor (GCD) can be calculated in following way;
Prime Factorization of 21
3 | 21 |
7 | 7 |
1 |
Prime factors of 21 are 3,7. Prime factorization of 21 in exponential form is:
21 = 31×71
Prime Factorization of 27
3 | 27 |
3 | 9 |
3 | 3 |
1 |
Prime factors of 27 are 3. Prime factorization of 27 in exponential form is:
27 = 33
∴ So by taking common prime factors GCF of 21 and 27 is 3
Factors of 21
List of positive integer factors of 21 that divides 21 without a remainder.
1,3,7,21
Factors of 27
List of positive integer factors of 27 that divides 27 without a remainder.
1,3,9,27
Greatest Common Factor
We found the factors and prime factorization of 21 and 27. The biggest common factor number is the GCF number.
So the greatest common factor 21 and 27 is 3.
Also check out the Least Common Multiple of 21 and 27
(i) The GCF of 21 and 27 is associative
GCF of 21 and 27 = GCF of 27 and 21
1. What is the GCF of 21 and 27?
Answer: GCF of 21 and 27 is 3.
2. What are the Factors of 21?
Answer: Factors of 21 are 1, 3, 7, 21. There are 4 integers that are factors of 21. The greatest factor of 21 is 21.
3. What are the Factors of 27?
Answer: Factors of 27 are 1, 3, 9, 27. There are 4 integers that are factors of 27. The greatest factor of 27 is 27.
4. How to Find the GCF of 21 and 27?
Answer:
Greatest Common Factor of 21 and 27 = 3
Step 1: Find the prime factorization of 21
21 = 3 x 7
Step 2: Find the prime factorization of 27
27 = 3 x 3 x 3
Step 3: Multiply those factors both numbers have in common in steps i) or ii) above to find the gcf:
GCF = 3
Step 4: Therefore, the greatest common factor of 21 and 27 is 3