To find the least common denominator, or lcd, you have to find the least common multiple, or lcm. To do that you find the multiples of each number until they equal each other. I set up a chart like this,
6 -
8 -
and then I start listing multiples so,
6 - 6, 12, 18, 24,
8 - 8, 16, 24,
I stop after I find a number they are both equal to. So to get to that number I would multiply 8 by 3, and 6 by 4. This gives me 24 as the lcd. If you need the lcd to add the fractions together, then whatever you did to the bottom do to the top. So 5/6 would become 20/24 and 3/8 would become 9/24.
Answer: 24
