Greatest Common Factor

Greatest common factor is the highest number that divides exactly into two or more numbers. 

• factors of $\;12\;$ are $\;1,\; 2,\; 3,\; 4,\;6\;$ and $\;12\;$
• factors of $\;16\;$ are $\;1,\; 2,\; 4,\; 8\;$ and $\;16\;$
• greatest common factor of $\;12\;$ and $\;16\;$ is $\;4\;$