All GRE Math Resources
Example Question #1 : How To Find The Lowest / Least Common Denominator
What is the least common denominator of and ?
To find the least common denominator of two numbers, it is easiest first to factor them into prime factors:
Now, you need to compare each number and choose the case in which the prime factor has the highest power. Therefore, since and are found only in , you will select those. You can take "either" . Finally, the in is the largest factor of . Your LCD is found by multiplying all of these together:
Example Question #2 : How To Find The Lowest / Least Common Denominator
To begin to solve this, you need to find the least common denominator of and . The easiest way to do this is to begin by factoring them into prime factors:
The LCD is found by selecting the largest power for each factor across the two values. Therefore, you will take ,, and from and the from the . Your LCD is therefore:
Now, apply this to your fractions:
Example Question #3 : How To Find The Lowest / Least Common Denominator
In simplest form,
First, find the smallest number that both and will factor into, which is .
This means that the fist fraction should be multiplied by and the second should be multiplied by .
Then, add the numerators while the denomenators stay the same:
Then, reduce the fraction to its lowest terms: