What is a percentage?
A percentage means per hundred. 15% is the same as 15 out of 100, or 0.15 as a decimal.
Percentage change vs percentage difference
Percentage change compares a new value to an original value, so direction matters. Percentage difference compares two values symmetrically using their average.
How to calculate VAT using percentages
To add 20% VAT, multiply by 1.20. To remove 20% VAT from a VAT-inclusive price, divide by 1.20 rather than subtracting 20%.