What is 87/100 - 7/8?

Here's how to subtract 7/8 from 87/100:

Step 1

We can't subtract two fractions with different denominators. So you need to get a common denominator. To do this, you'll multiply the denominators times each other... but the numerators have to change, too. They get multiplied by the other term's denominator.

So we multiply 87 by 8, and get 696.

Then we multiply 7 by 100, and get 700.

Next we give both terms new denominators -- 100 × 8 = 800.

So now our fractions look like this:

Step 2

Since our denominators match, we can subtract the numerators.

696 − 700 = -4

So the answer is:

Step 3

Last of all, we need to simplify the fraction, if possible. Can it be reduced to a simpler fraction?

To find out, we try dividing it by 2...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

Let's try dividing by 2 again...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

Let's try dividing by 2 again...

No good. 2 is larger than -1. So we're done reducing.