CODEWITHSUNDEEP
math
user2096512
user2096512

Reputation: 469

Reverse Percentage Lookup

This must be a simple question but I can't work it out!

I have a number that I know has been reduced to 70% of its original size, how do I find the original number?

For example I have the number 9.1, which is 13 x 70%, but what is the calculation for finding 13?

Upvotes: 0

Views: 2364

Answers (4)

Chuck Savage
Chuck Savage

Reputation: 11955

Another way to look at this, is you can calculate the inverse percent. Then multiply that by your reduced value to get the original value.

The percent was 70%.

70 percent is actually 70/100.

The inverse of that is 100/70. Because 100/70 * 70/100 = 1.

So, 100/70 (or ~1.42857) times 9.1 = 13.

Upvotes: 0

Ameen Rabea
Ameen Rabea

Reputation: 224

Taking your example. Say you have an item with DiscPrice = 9.1 and the discount amount is Disc = 30% and you wanted to calculate the original `SellingPrice' before the discount. Then the equation will be:

SellingPrice = ( DiscPrice * 100 ) / ( 100 - Disc )

// in your case then it will be
SellingPrice = ( 9.1 * 100 ) / ( 100 - 30 )
             = 13

See it in action: enter image description here

The above formulate for the decrease percentage calculation. There is also an increase percentage calculation here: https://stackoverflow.com/a/54125117/850840

Upvotes: 0

daniel gratzer
daniel gratzer

Reputation: 53871

Well if you have some number x, you're looking for a y so that

 y * 70% = x
 y * 70/100 = x
 y = 100 * x / 70

Upvotes: 1

Chris Taylor
Chris Taylor

Reputation: 47392

You want

originalNumber = reducedNumber / (percentage / 100);

for example

13 = 9.1 / (70 / 100)

Upvotes: 3

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