At present, there are 16 empty bottles. One bottle of mineral water can be exchanged for every 4 empty bottles. How many bottles can I drink at most if I don't pay?

At present, there are 16 empty bottles. One bottle of mineral water can be exchanged for every 4 empty bottles. How many bottles can I drink at most if I don't pay?


16 empty bottles can change 4 bottles of water, 4 bottles can change another bottle after drinking, so it's 5 bottles!