Who is asking: Student
There are many ways we use percentages in real life. The next time you go shopping, just check out the sale signs that say "30% off" or "50% off the lowest ticketed price" and you'll see just one of them. Knowing how to calculate percentages will allow you to determine the price of these items on sale. Once you get to the till to pay for the items, you will be charged sales tax, a fixed percentage of the price of the items. This is a very common use of percentages in real life.
Have a look at the food labels on something like juice or milk and see where it says "Percentage of recommended daily intake" for a certain portion or serving size. If you can calculate percentages you can determine how much of the food you need to eat or drink in order to get the full, or 100%, recommended daily intake. Another dietary consideration is fat intake and often foods will come saying only a certain percentage of calories come from fat.
Income tax that people pay on their earnings is a percentage of those earnings.
These are just a few ways we use percentages in real life, perhaps now you can think of a few of your own.