Value of PI in Rig Veda:

The number π is a mathematical constant. Originally defined as the ratio  of a circle's circumference to its diameter, it now has various equivalent definitions and appears in many formulas in all areas of mathematics and physics. It is approximately equal to 3.14159. It has been represented by the Greek letter "π" since the mid-18th century, though it is also sometimes spelled out as "pi". It is also called Archimedes’ constant.

Rig veda, source of infinite knowledge is believed to have proof of everything. A Sloka in the 10th book of Rig Veda appears to be written for praising Lord Indra. The technical translation of that Sloka gives the value of Pi up to 28 digits accurately. It is not until the invention of the computers that the western mathematicians could get this value up to 16 digits accurately. 

Vedic Numerical Code in the Vedas

In Sanskrit, the following Vedic Numerical code was used in many slokas

कादि नव

टादि नव

पादि पञ्चक

यद्यश- ्टक

क्ष शुन्यम्

“Kaadi nava

Taadi nava

Paadi panchaka

Yadyashtaka

Kshah sunyam”

Meaning:

Kaadi Nava Starting from ka, the sequence of 9 letters represent 1,2,..9

Similarly Taadi Nava , starting from ta

Paadi panchaka (1-5), starting from pa

Yadyashtaka (1-8) starting from ya

And ksha represents 0

In detail it is as follows:

ka (क) – 1, kha (ख) – 2, ga (ग) – 3, gha (घ) – 4,gna (ङ) – 5, cha (च) – 6, cha (छ) – 7, ja (ज) – 8, jha (झ) – 9

ta (ट) – 1, tha (ठ) – 2, da (ड) – 3, dha (ढ) – 4,~na (ण) – 5, Ta (त) – 6, Tha (थ) – 7, Da (द) – 8, Dha (ध) – 9

pa (प) – 1, pha (फ) – 2, ba (ब) – 3, bha (भ) – 4,ma (म) – 5

ya (य) – 1, ra (र) – 2, la (ल) – 3, va (व) – 4, Sa (श) – 5, sha (ष) – 6, sa (स) – 7, ha (ह) – 8

kshah (क्ष) – 0.

Based on this code there are many slokas in mathematics., e.g., the following is a sloka for Pi value:

गोपीभाग्- य मधुव्रातः श्रुंगशोदध- ि संधिगः |

खलजीवितखा- ाव गलहाला रसंधरः ||

gopeebhaagya maDhuvraathaH shruMgashodhaDhi saMDhigaH

khalajeevithakhaathaa- va galahaalaa rasaMDharaH

ga-3, pa-1, bha-4, ya -1, ma-5, Dhu-9, ra-2, tha-6, shru-5, ga-3, sho-5, dha-8, Dhi -9, sa-7, Dha- 9, ga-3, kha-2, la-3, jee-8, vi-4, tha-6, kha-2, tha-6, va-4, ga-3, la-3, ha-8, la-3, ra-2, sa-7, Dha-9, ra-2

3.141592653589793238462643- 3832792…

The above sloka has actually 3 meanings

1. In favor of Lord Shiva

2. In favor of Lord Krishna

3. The value of Pi up to 32 decimals.