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Calculating Percent
Name: Lawrence
Status: student
Age: 11
Location: N/A
Country: N/A
Date: N/A
Question:
MY MOM IS ON MY CASE. SINCE HOLIDAY SEASON SHE IS ALWAYS
ASKING ME WHAT THE PRICE OF SOMETHING IS WITH THE % DISCOUNT SIGN ON IT.
HOW DO YOU DO DISCOUNT OR PERCENT OFF OF A PRICE?
I DON'T WANT HER TO KNOW I DON'T REMEMBER SO A LOT OF TIMES I GO AWAY WHEN
SHE IS NEAR THE RACK.
Replies:
It requires doing some math in your head. If the price says "$Y," and the
discount tag says "X % off," the discounted price is $Y (1-X/100). In
English, that means you multiply the percent off by the price, divide by
100, and subtract this from the original price.
For example, if the price tag says $24.95, and the sign says "10% off," 10
times 24.95 is 249.5. Divided by 100, that's 2.50 (rounded off), which you
subtract from the original 24.95 to give approximately $22.50 (ok, $22.45,
but the whole calculation is easier if you realize that $24.95 is very
close to $25).
Richard Barrans Jr., Ph.D.
Chemical Separations Group
Hello,
A percentage simply means part per 100. So, one percentage of a hundred
dollar is one dollar. Five percentage of a dollar is five cents.
So, if a carton of milk is normally $2.99 and it on sale for 10% discount,
it means that you will take off 29.9 (actually 30) cents off the $2.99.
Your net cost will be $2.69. When you get a discount of 10% it means that
you pay only 90% of the regular cost.
I hope this help.
Good luck
Dr. Ali Khounsary
Advanced Photon Source
Argonne National Laboratory
``Per cent'' is French (roughly) for ``out of each hundred''. So a
discount of 30 per cent is a reduction in the price of 30 pennies out
of each hundred. Get it? Suppose the original price is 20 dollars =
2,000 pennies and the discount is 30 per cent. There are 20 hundreds
of pennies in 2,000 pennies. For each of these we get a break of 30
pennies, so we get a total break of 20 x 30 = 600 pennies, or 6
dollars. Hence the discounted price is 20 - 6 = 14 dollars.
Grayce
Lawrence,
To do a quick calculation, subtract the discount percentage from 100, and
use that number as a percentage multiplier to get the discounted price. For
example:
say there is an item for $45.00, with a 15% discount.
100 minus 15 is 85.
Your new price would be 85% of the old price, so you can multiply the old
price by 0.85, which is 85 percent written in decimal form.
0.85 times $45.00 is $38.25; this is the discounted price.
Thanks for using NEWTON, and many happy returns!
Richard R. Rupnik
Internal Quality Auditor
Lucent Technologies
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Update: February 2012
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