How high scores in an online brain teaser made mathematicians lie for three years
It might not yet be the phenomenon that is Wordle, but for hundreds of thousands of players, Digit Party has scratched the itch of a casual brain teaser to break up their day.
The online brain teaser Digit Party, which challenges players to arrange numbers on a 5-by-5 grid and earn points for identical numbers touching on adjacent or diagonal squares, was found to be lying about its high scores for three years. Mathematicians Vincent Vatter from the University of Florida and Robert Brignall from The Open University in the UK discovered the discrepancy.
They explained that while most puzzle scores were achievable, about 5% of the time, the game reported an incorrect maximum score. Vatter and Brignall determined that the game lied in 55 out of the 1,096 daily puzzles over three years, with an average error of just 2 points and a maximum error of 6 points. The researchers developed a method to compute the true high score for every possible combination of numbers by grouping puzzles with the same pattern of repeated numbers.
This reduced the optimization problem from 13.9 million potential digit sets to just 1,291 underlying mathematical problems, with only 400 requiring trade-off analysis. The findings were published in Math Horizons on August 25, 2026.
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