Pi, the ratio of a circle’s circumference to its diameter, is possibly the most well-known concept in mathematics. We hold contests for people to recite this irrational number to the greatest number of digits, and as knitters we use it as a formula for creating circular shawls. We even celebrate “Pi day” on March 14th (3-14) by eating pies.

And as with Buffon’s Needle Problem, Pi also shows up in quantum mechanics, the theory of relativity, number theory and now, in more than one way, this cowl.