How to Add 10 Percent to a Number OR

How to Add 10 Percent to a Number OR

How to Add 10 Percent to a Number


Here’s an interesting experiment—you’ll learn how to add ten percent to any number. You also figure out that this technique is perfect for calculating what-if projections.


In some math problems, you might know the percent increase or decrease and the new amount, and need to work out the original amount. For example, you know a bed with a $280 sale price has been reduced by 30 percent. To work out the original price of the bed, you have to establish what percentage of the original price the sale price is. The original price is 100 percent and 30 percent has been taken off, so the sale price is 70 percent of the original price. Divide the sale price (280) by the numerical value of 70 percent, or 0.7, to work out the original price. The answer is 400, so you know the original price of the bed was $400.

As your maths skills develop, you can begin to see other ways of arriving at the same answer. The laptop example above is quite straightforward and with practise, you can use your mental maths skills to think about this problem in a different way to make it easier. In this case, you are trying to find 20%, so instead of finding 1% and then multiplying it by 20, you can find 10% and then simply double it. We know that 10% is the same as 1/10th and we can divide a number by 10 by moving the decimal place one place to left (removing a zero from 500). Therefore 10% of £500 is £50 and 20% is £100. (Source: www.skillsyouneed.com)


Note: There is no standard equation for percent difference for all circumstances. The equation used here divides the difference between the two values by the average of the two values (see equation below). Some cases may require you to divide by the minimum of the two values or the maximum of the two values, etc. Please check that the equation used here fits your circumstance.

Joey is looking at this new smartwatch that he wants to buy. It costs $359 and it comes with all the apps that he uses. He can check stock prices, check flight information, and shop online through this watch. Just yesterday though, Joey received an advertisement in the mail telling him that this watch will be 10 percent off in a week! That's perfect for Joey as he is getting paid in a week. He'll have the money to pay for this watch. But how much of a discount will Joey get with this 10 percent? How much will Joey save? Let's calculate our 10 percent discount. (Source: study.com)


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