English: Glyph variants of Greek letter Pi in medieval and early modern minuscule handwriting, according to C. Faulmann, Schriftzeichen und Alphabete aller Zeiten und Völker, Wien 1880. https://commons.wikimedia.org/wiki/File:Greek_minuscule_Pi.svg 1280px-Greek_minuscule_Pi.svg.png (1280×455)
Glyph variants of Greek letter Pi in ancient cursive handwriting, according to C. Faulmann, Schriftzeichen und Alphabete aller Zeiten und Völker, Wien 1880. 2000px-Greek_cursive_variants_Pi.svg.png (2000×711)
Pi is indeed a fascinating number. Memorizing pi is a feat (43,000 digits by Krishan Chahal—took him 5 hours 21 minutes), but you’ve probably heard of that already. What I find more interesting is how few digits of pi you actually need to get anything done. If you wanted to draw a circle around the known universe (about 10 to the 26th power meters in diameter) and be accurate to the diameter of a proton (10 to the -15 power meters) you’d only need 43 digits of pi.