Contents.

Constants

The numbers themselves.

1. No. 3.1π — It does not close.

Approximations

Close, and by how much.

1. No. 3.1422/7 — Close enough to share.
2. No. 3.1415355/113 — Six digits, six places.

Kitchen

Pie, treated with the same care.

1. No. 3.141Pie — The crust is a proof.
2. No. 3.14159Crust — The edge grows more slowly than the middle.
3. No. 3.1415926Slice — Half the radius, times the crust.

Chance

Constants that turn up in random things.

1. No. 3.141592Needles — π, found by dropping things.

Proofs

What can be shown, and what cannot.

1. No. 3.14159265The Square — The one shape it will not become.

Series

Sums that go on forever and still arrive.

1. No. 3.141592653Patience — One, minus a third, plus a fifth, and so on.

Growth

Things that feed on themselves.

1. Supplement 2.7Interest — Growth that never stops to count.
2. Supplement 2.71Rise — Half full, one doubling before the top.

Forthcoming

1. No. 3.1415926535Steam — How long should a pie rest, and can the resting be written down?
2. No. 3.14159265358Lattice — What does a lattice top count?
3. Supplement 2.718Starter — What does a sourdough starter know about e?