If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Lesson 2: Common denominators

# Common denominators: 3/5 and 7/2

Learn how to rewrite fractions with different denominators as equivalent fractions with a common denominator. Watch how to visually represent this process and apply it to solve problems.

## Want to join the conversation?

• how can you find common denomenators in really huge fractions like 5/101 and 6/500
• It's the exact same process with finding the greatest common denominator and everything. Except, for the numbers 101 AND 500 like you mentioned in your example fractions you might find yourself having to multiply the two numbers together in order to find the common denominator. So you would multiply: `101*500` which ends up equaling `50500`. That would be the common denominator.
• What are common fractions and least common fractions?
• And common fractions are the answers or multiple which is in both numbers
• what if the fraction is a mix number
• You turn it back into a improper fraction. For example, 2 1/3. You multiply the whole number and the denominator, which in this case would be 2 x 3. That equals 6. Then, add that on to the numerator. The numerator is 1, so you add 6+1. That equals 7, so that is the numerator of the improper fraction. The denominator always stays the same, so the improper fraction of 2 1/3 is 7/3.
• what is 1/2-1/5
• (1/2) =0.5
(1/5) =0.2
= 0.3
= 3/10
• this is difrent from what im learning in class
• It can be different because they are from Khan academy and that is the way they teach or were taught so that is how they are different and they don't know the way your class
• is 3/5+2/6=10/18
• No, 3/5+2/6 = 3/5+1/3 = 9/15+5/15 = 14/15.

Have a blessed, wonderful day!
• Why do people make fun of khan academy?
• i dunno
• so 7/2 would be 14/4?
(im asking this half way through the video btw)