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# Comparing fractions 2 (unlike denominators)

Sal compares fractions by finding a common denominator.   Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

• Can I do it this way?
21/28 = 0.75
6/9 = 0.67
• well i agree with you but you never know so watch over again and catch the mistakes
• what are Prime Numbers,Composite Numbers and LCM & HCF is there series of videos for these topic on khan academy
• Describe 2 ways to compare 5/12 and 5/8 (not using common denominators or cross product methods).
• One way to compare is that 5/12 is less than 5/8 because 5/12 is less than half of 12 and 5/8 is greater than half of 8.
• Where do get that 7 and 3 from the first step
• what do you mean?
if you mean series it will be( 7 , 3 ,-1 , -5 , and so go on and and on ) all you do is adding at every step (-4)
• what does LCD stand for
• Lowest/Least Common Denominator
(1 vote)
• i'm so confused i really don't understand this at all
• Has anyone noticed sal repeats things he say sometimes
• What happens if both of the numbers in both
fractions dont go into to anything?
F
• There is always a common multiple for the 2 denominators. If they share no common factors, then the common multiple is created by multiplying the 2 numbers.
For example, the common multiple of 10 and 3 = 10*3 = 30
(1 vote)
• hello everybody its pinky star haven the smartest gartest martest best human being EVER! 6/8 is smaller then 7/12 cus the denomenater is bigger I bet I'll get the most votes if your one of my thousend's of fans that i'll bet are out there be sure to comment bellow
• That is incorrect and you misspelled every single word.
(1 vote)
• before I saw the end i was like:
you could just do 9 * 21 and 28 * 6
and that results in : 186 > 168
you don't actually have to multiply the denominators
that's just extra work isn't it :)? at-least when comparing fractions
if on the other hand you have to simplify after ...