Project Euler 4 Mystery Cache

Acknowledgements

This cache was inspired by Project Euler.

General notes

• To solve Project Euler puzzles, you will probably have to write a computer program.
• Many of the containers are small, and contain neither pen nor pencil.
• There are explicit finding notes in each geochecker.

The puzzle

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.

Define f_i(n) to be the first i digits of the largest palindrome made from the numbers {100,101,...,n}.

For example, the largest palindrome using the numbers between 100 and 200 is 36863, and so f₂(200) = 36.

To find this cache, first calculate:

• f₂(747),
• f₂(390),
• f₃(750),
• f₃(615) - f₃(564),
• f₁(273),
• f₃(911).