The definition of percent is parts per hundred.  We can use manipulatives to help show that percent is out of 100.

Let's use graph paper with 100 squares to demonstrate.

Since 23 squares are shaded in out of 100
 the ratio is 23 to 100 or 23/100.  The percent then is 23%.

Some percents can be reduced when in fractional form.  In the first example 23 is prime so 23/100 is in lowest terms.  Take a look at this example...

On this graph paper 35 of the squares are shaded.  The ratio here is 35 to 100 or 35/100.  This can be reduced to 7/20.  (Be sure you recognize these are equivalent fractions.)  Either way, the percent is 35%.

Let's Practice!