# Basic Math

posted by .

I need help adding fractions with different denominators.

Here is the problem...

1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6

I can see that the demoninators increase. Since they are both addition and subtraction, how do I do this problem?

Thanks, Walter, New York.

• Basic Math -

1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6

You need to find the common denominator -- the smallest number divisible by each of the denominators.

One way to do that is to find the multiples of the largest.

6, 12, 18, 24, 30, 36, 42, 48, 54, 60

Ahh -- the common denominator is 60.

1/2 = 60/2 = 30/60
1/3 = 60/3 = 20/60

That should give you a good start.

• Basic Math -

Okay, Now that the common demoninator is 60, I now multiply. But where do I start? for example, I just leave the 1 alone because its a whole number. So now I multiply the 1/2 to 1 * 30 = 30 and 2 * 30 = 60 Do I do the same for the 1/3 and so on?

• Basic Math -

1/2 = 30/60
1/3 = 20/60

What do you think 1/4 equals?

• Basic Math -

1/4 = 15/60
1/5 = 12/60

What do you think?

• Basic Math -

solve 5/30+3/40+1/8

• Basic Math -

what is 5/30 + 3/40 + 1/8