March 13, 2026 4 min read Add Us On Google Add SciAm Mathematicians find one pi formula to rule them all A mixture of AI and algorithms uncovered a hidden structure spanning 2,000 years of equations for pi By Lyndie Chiou edited by Clara Moskowitz Jeffrey Coolidge/Getty Celebrate Pi Day and read about how this number pops up across math and science on our special Pi Day page . For more than two millennia, mathematicians have produced a growing heap of pi equations in their ongoing search for methods to calculate pi faster and faster. The pile of equations has now grown into the thousands, and algorithms now can generate an infinitude. Each discovery has arrived alone, as a fragment, with no obvious connection to the others. But now, for the first time, centuries of pi formulas have been shown to be part of a unified, formerly hidden structure. Divide any circle’s circumference by its diameter and you get pi. But what, exactly, are its digits? Measuring physical circles won’t tell you—your tools are too clunky to discover pi’s endless numerals. Uncovering its true value requires something much more powerful: a formula. It all started with Archimedes , who developed the world’s first known mathematical proof for pi’s value. He thought of a circle as an infinite-sided polygon with sides of zero length. The math to handle infinitesimals (calculus) wouldn’t arrive for another 1,900 years, so instead he circumscribed 96-sided polygons on the outside and inside of a circle and used geometry to calculate their perimeters. He was able to determine that pi fell somewhere between 3.140845... and 3.142857..., trapping it in a range. His rigor stood for 1,600 years. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing . By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. Then, around the 14th century, Indian mathematician Madhava of Sangamagrama provided the first exact formula, expressed as an infinite series—a sum of endlessly many terms that, if you could somehow add them all up, would yield pi exactly. The catch: his series converged agonizingly slowly, requiring hundreds of terms just to nail down a few decimal places. More than three hundred years later Leonhard Euler discovered another series that converged faster. And in the early 1900s, the mathematician Srinivasa Ramanujan produced formulas that are still revered for their efficiency today. Amanda Montañez; Source: “From Euler to AI: Unifying Formulas for Mathematical Constants,” by Tomer Raz et al. Preprint posted November 16, 2025 to https://arxiv.org/pdf/2502.17533 ( reference ) Each equation seemed unrelated to the others. But in late 2025, a team of seven AI researchers at the Technion–Israel Institute of Technology found a previously unknown mathematical structure underlying hundreds of pi formulas, including those of Archimedes, Euler and Ramanujan. “It’s not every day that you get to cite Archimedes,” says Ph.D. student Michael Shalyt, part of the team. The structure, called a conservative matrix field, or CMF, acts as a kind of mathematical common ancestor, showing how formulas that look nothing alike turn out to be different expressions of the same underlying object. The project grew out of group head Ido Kaminer’s 2019 Ramanujan Machine, an AI bot that seeks out new conjectures for calculating mathematical constants. Anyone can download the software for free, and many have used it to find new pi formulas to join the heap. The bot’s unconventional approach was a viral success, if not taken entirely seriously by mathematicians. “When we started doing AI research in this area of math,” Kaminer says, “it was seen as a fringe idea.” But as the machine and other mathematicians kept churning out formulas, eventually the question became unavoidable: Were any of them connected? The group, who also have backgrounds in areas such as physics and math, approached the problem like experimentalists and decided to gather a dataset. Tomer Raz, then a master’s student at Technion, wrote code to download every math paper that had ever been uploaded to the preprint server arXiv.org, running his laptop seven days a week, 24 hours a day, for six weeks to download 455,050 papers at a slow enough rate to respect the website’s limit. The group then deployed GPT-4o in combination with specialized algorithms to detect pi-related equations, translate them into executable code, and remove trivial duplicates. From nearly half a million papers, they extracted 385 unique formulas, including about 10 percent that originated from the Ramanujan Machine. For the next step, they recast the 385 equations into the same format—a special type of infinite series. But the expres