← 📐 Mathematics · usually met in Std 6-12
The ratio of any circle's circumference to its diameter. The same number for every circle, and its decimals never end or repeat.
Measure round any circle and across it, divide one by the other, and you get about 3.14159 — whether the circle is a coin or a stadium. That constancy is what makes it a fundamental constant rather than a measurement. Because it is irrational, no fraction gives it exactly, and 22/7 is a convenient approximation rather than a value.
Aryabhata gave a value equivalent to 3.1416 in the fifth century and described it as approached rather than reached. Madhava and the Kerala school, from the fourteenth century, found infinite series that converge to it — work that anticipated parts of calculus by centuries. Computers have now calculated it to many trillions of digits, which is useful mostly as a test of the computers.
Want to see it moving? Search YouTube for “Pi” ↗ — we send you to the search rather than to one video, because a link to one video eventually rots.
This entry was written for Star Student in our own words — it is a summary, not a source. Here is where the people who actually hold these facts keep them. Go and check.
Your own textbook ↗Balbharati publishes the textbooks free to read online. Your chapter is the thing to check first — an encyclopedia is a summary, and the syllabus is the syllabus.Last gone through: 1 October 2026 · How these entries are written
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