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View Full Version : How to find the lcd of a fraction


alternap18
Sep 25, 2010, 10:12 AM
? I'm trying to find the lcd of 3/35+6/45
How do you find it do you keep on rising the numbers like 45+45+45 until u get a large common denominator

donf
Sep 25, 2010, 10:26 AM
There are several methods, but the most quick and easiest is to multiply both denominators together to get the new denominator, then calculate the new numerators.

Unknown008
Sep 25, 2010, 10:31 AM
Well, there is a common way of finding the least common multiple easily. Set out the prime factors of the numbers and 'merge' the common factors.


35 = 5 x 7
45 = 3 x 3 x 5
LCM = 3 x 3 x 5 x 7