You can MULTIPLY fractions together without finding a common denominator. To ADD or SUBTRACT you WILL have to find the common denominator
A Common denominator for 2 and 3 is........... '6'
So, convert them both to 'sixths'
1/2 x 3/3 = 3/6
1/3 x 2/2 = 2/6
Substitute 1/2 - 1/3 = 3/6 - 2/6 = 1/6
~jc
