What is the greatest common factor of 42, 63, and 105?
Common factors are just
Greatest Common Factor is
Writing each number as the product of its prime factors is a quick way of finding the HCF and LCM of any number of values.
What is the greatest common factor (GCF)?
That is the largest number that will divide into all those given.
To find it, the smallest prime numbers should be divided into each one. Prime numbers are: 2, 3, 5, 7, 11, 13, 17, 19.
Each division results in the same number, so that is the GCF.