Chem – Greatest Common Divisor


Next, we tackle the concept of the greatest common divisor. This is something you most likely used in math when you were working on chapters with fractions in them. The greatest common divisor is commonly used in math when you are creating fractions in the lowest terms possible. Simply put, the greatest common divisor is a number (for our purposes, only integers) that is the largest possible number you can divide into a group of two or more numbers. This concept will be used in a very limited way throughout the first half of the chemistry class.


Examples: Give the greatest common divisor between these two numbers. VIDEO demonstration of the greatest common divisor examples below.

8 and 10 2
100 and 25 25
36 and 45 9


So for the first example, I tried going up from the bottom of the integer scale. I started with 1. 1 divides into 8 and 10. Let’s try going up then. 2 divides into 8 and 10. 3 does not. 4 does not. This is the point where I will usually stop. So, the only answer I am left with is 2.


PRACTICE PROBLEMS: Find the greatest common divisor.

25 and 10 5
14 and 28 7
12 and 9 3
33 and 55 and 121 11


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