A wagering requirement represents the number of times you must play through a given bonus before withdrawing any winnings. Let's say claim a 100% up to €30 bonus with 15x wagering requirements. If you do the math, it will look like this:
Meaning, to make a withdrawal, you must bet a total amount of €450. Now, let's say the casino requires you to put your deposited amount in the equation, too. In this example, we'd say that you deposited the maximum of €30.