Understanding e to the pi i - "An intuitive explanation as to why e to the pi i equals -1 without a hint of calculus. This is not your usual Taylor series nonsense." (via via; reddit; previously) [more inside]
Happy Tau Day! τ (2 × π, that is, 6.28...) is the number of radians in a turn. Translating the digits to notes even makes beautiful music. (By comparison, what pi sounds like). Previously.
Whether its crocheted hyperbolic models or Lorenz manifolds, a lace pi shawl or knit Fibonacci socks, some math geeks find expression in the fiber arts.