Source: Mailed to me by JDGM ("regular commenter JDGM")
The integers greater than zero are painted such that:
• every number is either gold or silver.
• both paints are used.
• silver number + gold number = silver number
• silver number * gold number = gold number
Given only this information, for each of the following decide whether it is a gold number, a silver number, or could be either:
1.) gold number * gold number
2.) gold number + gold number
3.) silver number * silver number
4.) silver number + silver number