Here's how:
1. The Code: The keypad has 10 buttons representing the numbers 0-9. Each button is also marked with a symbol representing a specific element.
2. The Clue: The Declaration of Independence has several hidden symbols within the text. These symbols, when deciphered, reveal the elements corresponding to the keypad buttons.
3. The Solution: Ben uses his knowledge of historical codes and the clues in the Declaration to match the symbols to the corresponding elements on the keypad. This determines the correct sequence of numbers to unlock the treasure.
Essentially, Ben uses historical context and hidden clues to solve the puzzle, not by cracking the code itself.
It's important to note that the movie takes some liberties with historical accuracy and the process of deciphering codes. However, it's a fun and engaging example of how historical knowledge can be used to solve puzzles.