Skirt is worked flat and then seamed in a spiral. Adding the waistband is done in the round. The final border on the bottom is worked in rows. The number “Pi” starts at your right hip and you can make the skirt as long as you’d like, finishing so that the “end” of Pi stops in front of your right leg.

The width of the strip increases by one stitch whenever your row count is one of the Fibonacci numbers. The Fibonacci sequence is the sequence of numbers starting with 0 and 1 so that each number is the sum of the previous two numbers: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, etc. See how 8+13 = 21, 21 + 13 = 34, etc.

I’ve included a list of digits of Pi with the prime-th digits colored blue and a list of the first few Fibonacci numbers; it’s unlikely you will need to go higher than that!

Don’t forget that Pi day is coming up on 3/14/15!