In this video, we learn how to increase or decrease by a percentage. First, to increase you will need to find what the percent of the number is. To do this, you will find 10%, which should be very easy. As soon as you've found this, you can add or subtract to find the percent you need. Then, add this onto the original number and you'll know the percentage. To decrease the percentage, you will do the same type of equation. Except, you will need to subtract as you go to finish the problem. When done, you will know the answer!