The above answer is not currency dependent, whether you use US dollars, euros or other currencies.
How Can I Calculate 100% off 20
If there is an 20% discount on a product(100) 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 $100.
Step2
Meaning of discounts
The discount is 20%, so we have saved 20 out of 100.
Step3
Each part of the original price
We divide $100 into 100 parts, so each part is $100 / 100, or $1.
Step4
Discount Value
We have 20 parts, each of which has a value of 1, or $20.
Step5
The Results
The original price is $100, and the discount value is $20, so we get a final price of $100 - $20, or $80.