Bottle deposit programs are one way to encourage higher recycling rates. explain how they work

When buying different beverages from a person distributing, a deposit needs typically to be paid to the distributor from the containers that have been taken. However, the distributor will issue a refund once the bottle that was taken has been returned to the place of purchase

Therefore, the distributor will reimburse the redemption of the retailer the amount that was deposited for every container. The additional handling fees usually added in some countries. The deposits that remain unredeemed are taken to the state or kept by distributors.

81 is a composite number.