Greatest Common Factor of 15 and 21
Help is NOT a good title for this post. It should be Math, etc.
Sra
http://www.math.com/school/subject1/lessons/S1U3L2GL.html
http://www.helpwithfractions.com/greatest-common-factor.html
Note that you're looking for the GREATEST common factor, not the LEAST common factor.
To find the greatest common factor (GCF) of 15 and 21, you can use the following steps:
1. List the factors of both numbers.
The factors of 15 are: 1, 3, 5, 15.
The factors of 21 are: 1, 3, 7, 21.
2. Identify the common factors.
The common factors of 15 and 21 are: 1 and 3.
3. Determine the greatest common factor.
The greatest common factor of 15 and 21 is 3, as it is the largest number that both 15 and 21 can be divided by evenly.
Therefore, the greatest common factor of 15 and 21 is 3.