# Percentages: Is / Of = % / 100

Sometimes you are given a number and asked what 30% of that number is. Other times you are given a number and asked what percentage it is of another number. The key thing to always remember is:

• is / of = % / 100

As you can see, there are three variables and then a constant of 100. Anytime you are given a problem you will be given 2 of the variables and you must find the missing variable. Simply plug in the numbers into the equation.

Example: What is 40% of 60?

• First, identify the variables.
• It says 40% so we know our percent.
• It says "of 60" so we know our "of"
• Now we plug in our known variables to solve for "is"

We now have ( is / 60 ) = ( 40 / 100 ). With this equation we first multiply 40*60 = 2400 and divide by 100 = 24.

Answer: 24 is 40% of 60.

Watch the math video below for a detailed explanation!

### Practice Math Problems

1. What is 30% of 50 ?
2. What % is 12 of 48 ?
3. 26 is 65% of what number ?
4. What is 35% of 20 ?
5. What % of 20 is 4 ?
6. 40 is what % of 800?
7. 30 is 30% of what number?
8. 300 % of what number is 30 ?