How to Figure the Percent of Increase or Decrease

You may not need all the algebra you learned in high school on a day to day basis, but there are some basic math skills that would be nice to know. One is figuring the percent of increase or rate of change. Would you like to know how much your Performance Bonus has increased by percentage? How much of a raise you actually got? How much that suit is really marked down? Figuring the percentage of increase is actually an easy thing to do.

First you need to know the amount now, and the amount originally. Then you subtract the smaller amount from the larger one. Divide the number you got by the amount of the original. Your answer will be a decimal number. Multiply that by 100. In mathematics, this can be shown as a fraction as in:

amount of change percent
______________ = __________
original 100

Let's take some examples. If your page views count the last time you received your performance bonus was 11000, and now they show 13,000, subtract the diffference and you will get 2000. Are you with me so far? Now take 2000 and divide it by the original (before the change). So 2000 divided by 11000 gives us 0.18. Multiply that by 100 and you get 18, which means an 18% increase. Good job!

That one looks like this:

13000-11000 ?
___________ = ______
11000 100

Let's take another example. You see a dress for $24, but it is now marked $18. What percentage off is the sale price? Subtract 24 - 18 and that equals 6. Now divide six by the original amount 6 divided by 24, and you get 0.25. Multiply that by 100 and you get 25% off that dress!

24-18 ?
_____ = _____
24 100

Now, what if your hourly pay is now $9.00, and your boss wants to offer you $10.98? What percent raise is that? I bet you can do this one! Subtract 10.98 - 9.00 and you get 1.98. Divide 1.98 by 9 and you get 0.22. Multiply that by 100 and you get 22% increase in your hourly pay! Wow! Nice boss!

10.98 -9.00 ?

_________ = _____

9.00 100

This works whether the percentage of change is an increase or a decrease. Now you can impress all your friends with your math skills, especially if you have a calculator nearby! Now if you can just talk your boss into giving you a 22% raise!