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Mathematics

The Traveling Salesman Problem and Why It Is Hard

Quick fact

For 15 cities, there are over 43 billion possible routes to check—but a computer can handle it. However, for 100 cities, the number of routes exceeds the number of atoms in the entire universe!

Why this is interesting

Imagine you have to visit 15 cities by car and return home. You’d probably think, ‘How hard can that be?’ But the Traveling Salesman Problem turns out to be one of the most fiendishly difficult puzzles in all of mathematics.