[Reverse Process]

A peasant, buying goods, paid the first merchant half of his money and another 1 ruble; then he paid the second merchant half of the remaining money and another 2 rubles, and finally, he paid the third merchant half of what was left and another 1 ruble. After this, the peasant had no money left. How many rubles did he have initially?
Before coming to the third merchant, the peasant had 1 ruble and as much again - a total of 2 rubles. Before coming to the second merchant, he had $2+2$ = 4 rubles and as much again - a total of 8 rubles. Finally, before coming to the first merchant, the peasant had $8+1=9$ and as much again; so initially, the peasant had 18 rubles.

## Answer

18 rubles.