So, what happens when you can't make the denominator a pretty power of 10?

Well, we just use long division and do a little rounding.  Let's just make our answers go to one decimal point.

Let's try one:

Convert1 / 3
to a percent:

First, we use long division to convert the fraction to a decimal...

long division work for 1.00 divided by 3

Just like we thought, it's giving a repeating decimal:

1 / 3 = .3333...

So, we can give our answer as

1 / 3 = .333 with a bar over the last 3 = 33.3% with a bar over the last 3

Or we can round off and approximate the answer as

1 / 3 is approximately equal to .33 = 33%
Notice that I used a wavy equals for "approximately equal!"