On a chess board, we place a pawn in its usual starting position, in the second row. We want to crown the pawn by taking it to the last row following the following rules:

- The pawn will advance as many squares as faces we get from the launch of a certain number of coins, which we assume balanced.
- We can use as many coins as we want, but once we choose the number of coins to be thrown we cannot change it throughout the game.
- We must reach the eighth row with the exact number of faces we need to crown.
- If we only get crosses or if we get more faces than we need to crown, the pawn will not move and we will launch again.

**How many coins would you choose to try to crown in the least possible number of throws?**

Extracted from the elmaquinadeturing page

#### Solution

**the optimal number of coins to use is 4**. If we choose less than 4 coins we throw so few that it will take us a long time to crown, but if we throw more than 4 the rule of *"Crown with the exact number of faces"* It can cause us to lose a good number of turns if we fall in a row close to 8.

The demonstration is extensive and is included in this document written by Javi Oribe.