Adding and Subtracting Fractions with DIFFERENT denominators

Don't make the mistakes everyone else makes!

What's 1/2 + 1/5?
If you answered 2/5, well no, that's too small.

If you answered 2/2, well no, because if you draw them both, they don't make a whole.

If you answered 2/10 well:
because 1/2 = 5/10
so how could 1/2 + 1/5 = 2/10, which is less than 5/10!

So, when you're adding (or subtracting) fractions with DIFFERENT denominators, you can't just do what we normally do (add the numerators and keep the denominators the same). What you need to do first is make the fractions have the SAME denominator. This means you need to find a COMMON denominators that they can both become equivalent to before you add or subtract at all.

Finding Common Denominators

Adding fractions: different denominators: To solve this problem, we need to find the least common multiple to get at the common denominator.

Subtracting fractions: different denominators: If you conquered adding fractions with different denominators, then subtracting fractions will be a snap. Don't worry...we'll take it slow and explain every step.

Now play Different Denominator PacMan.

No comments:

Post a Comment