The thread is about most ancient & world's greatest mathematician and astronomer, Aryabhatta. Aryabhatta was born around 475 AD, and had already published his most significant work, "Aryabhatiyam", by the age of 23. Though Aryabhatta has made innumerous contributions to both mathematics and astronomy, in this post, I would like to specifically elucidate how he was the first person to identify the irrationality of possibly the most enchanting and intriguing of numbers, Pi. Aryabhatiyam is also referred to as Ashtamkara and also as Aryashastasashta (108 verses), but is now popularly called Aryabhatiyam. The Sanskirt verse describing Pi is given below: The English interpretation of the above Shloka would be: Add 4 to 100, multiply by 8, then add 62000, then divide by 20000. The result is "approximately" circumference of a circle of diameter 20000. The answer of the above calculation is 62832/20000 = 3.1416. By using the word"Asanna"(last word in the Sanskrit verse), Aryabhatta clearly states that the value so found is not exact, but an "approximate" one, something that was "approaching" the exact value. So he is referring to it being irrational. This is quite a significant contribution, as it was not until the 17th century that Pi was proved to be irrational in Europe.