The above answer is not currency dependent, whether you use US dollars, euros or other currencies.
How Can I Calculate 90% off 80
If there is an 80% discount on a product(90) on sale, here is a quick calculation of the final price and what the savings will be, The procedure is as follows
Step1
The need to be known
In the case above, the price of the product is $90.
Step2
Meaning of discounts
The discount is 80%, so we have saved 80 out of 100.
Step3
Each part of the original price
We divide $90 into 100 parts, so each part is $90 / 100, or $0.9.
Step4
Discount Value
We have 80 parts, each of which has a value of 0.9, or $72.
Step5
The Results
The original price is $90, and the discount value is $72, so we get a final price of $90 - $72, or $18.