Use the formula π = circumference ÷ diameter
Measure a circle’s circumference
Measure the same circle’s diameter
Divide the circumference by the diameter
Use a calculator or software for higher precision
Use the Gregory-Leibniz series: π = 4 × (1 – 1/3 + 1/5 – 1/7 + …)
Use the Nilakantha series for faster convergence
Use the Monte Carlo method by comparing random points in a square and inscribed circle
Use polygon approximation by increasing the number of sides of an inscribed or circumscribed polygon
Use numerical algorithms such as the Gauss-Legendre algorithm
Use Ramanujan-type formulas for rapid computation
Use built-in constants in programming languages and math libraries