Wagering requirements are calculated on your free spins wins. If you win £10 and need to complete the wagering requirements of 40x the winnings. To calculate how much you have to wager, just multiply the winnings with the wagering requirement: £10 x 40 = £400. So to be able to turn your winnings into withdrawable cash funds you will need to wager £400 on eligible slots and other casino games at the casino.