What is the Greatest Common Factor of 7 and 21?
Greatest common factor (GCF) of 7 and 21 is 7.
GCF(7,21) = 7
We will now calculate the prime factors of 7 and 21, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 7 and 21.
How to find the GCF of 7 and 21?
We will first find the prime factorization of 7 and 21. After we will calculate the factors of 7 and 21 and find the biggest common factor number .
Step-1: Prime Factorization of 7
Prime factors of 7 are 7. Prime factorization of 7 in exponential form is:
7 = 71
Step-2: Prime Factorization of 21
Prime factors of 21 are 3, 7. Prime factorization of 21 in exponential form is:
21 = 31 × 71
Step-3: Factors of 7
List of positive integer factors of 7 that divides 7 without a remainder.
1
Step-4: Factors of 21
List of positive integer factors of 21 that divides 7 without a remainder.
1, 3, 7
Final Step: Biggest Common Factor Number
We found the factors and prime factorization of 7 and 21. The biggest common factor number is the GCF number.
So the greatest common factor 7 and 21 is 7.
Also check out the Least Common Multiple of 7 and 21