Math CentralQuandaries & Queries


Question from Donna:

What is the percentage of savings if I bought an item for $98.60 that was $152.23 and something for $96.48 that was $136.65?

Hi Donna,

To find the percentage change between two numbers you find the change, the difference between the two numbers, divide by the starting number and then multiply by 100. If the change is a decrease then the percentage change is a percentage decrease and if the change in an increase then the percentage change is a percentage increase. For example if you purchased a painting for $300 and later sold it for $500 then the change is $500 - $300 = $200. The starting value was $300 so the percentage change is

($500 - $300)/$300 × 100 = 200/300 × 100 = 66.7%

Thus the value of the painting increased by 66.7% of the original price, a 66.7% increase.

If the normal price of an item is $126.75 and you bought it on sale for $98.99 then the percentage change is

($126.75 - $98.99)/$126.75 × 100 = $27.76/$126.75 = 21.9%

The price you bought it for was less than the original price so this is a percentage decrease of 21.9 percent. Hence you saved 21.9% of the original price.

I hope this helps,

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