### What is 1 3rd plus 1 5th?

To do this, you need to find the lowest commen denominator of 1/3 and 1/5. The lowest common multiple of the two denominators, 3 and 5 is 15, so you convert each fraction to a fraction with a denominator of fifteen and then add the numerators: (1/3) + (1/5) =(5/15) + (3/15) =(5+3)/15 =8/15 Therefore your answer is eight fifteenths.