The constants that run the universe, as numbered exhibits — provenance, exact or measured, and what each does. Includes a live pi engine (Machin's formula computed with big integers), a golden-ratio p.
Machin's formula from 1706: π = 16·arctan(⅕) − 4·arctan(&frac1;239). The engine below runs that formula with big integers at 10,000-digit precision behind the scenes, then prints as many digits as you ask. No lookup table, no network: the digits are computed.
Values follow NIST CODATA 2018 and the SI redefinition of 20 May 2019. Exact values (defined, not measured) are marked exact; the rest are measurements with the stated uncertainty. When a number is contested — like the Hubble constant — the treasury says so.