Pi Formula: Noah's Ark
The Wallis product for π, whose factors come in pairs like animals boarding the ark.
Use this cartoon
Free for classrooms, worksheets, slides and other non-commercial use under CC BY-NC 4.0, with credit to Ben Orlin.
Cartoon by Ben Orlin, Math with Bad Drawings. https://cartoons.mathwithbaddrawings.com/2016-03-14-pi-formula-noah-s-ark/ (CC BY-NC 4.0)Transcript
"Noah's Ark" [animals two by two] "fraction factors like a zoo: odds and evens two by two…" π/2 = 2/1 × 2/3 × 4/3 × 4/5 × 6/5 × 6/7 …