**Color Counting**

Last Monday we learned to count to 100, and even 1000 on our fingers, and I showed what counting in binary sounds like on the piano. The trick is to let some fingers stand for numbers bigger than 1, so that when you raise several fingers, they can add up to a much bigger number.

Here’s the slideshow from the event. And here’s a video replay of the event.

**Further Finger Math**

**Flash Anzan demonstration. **Blindingly fast mental calculation using an imaginary abacus.

**Short documentary video** on Flash Anzan.

**Article** by math journalist Alex Bellos:

**Abacus basics****. **How the soroban (Japanese abacus) works.

**Abacus demo**. A young girl adds big numbers superfast. Good demonstration of what fluent abacus looks like. The abacus is still taught in much of Asia, and there are schools all over the world that teach it.

**Chisenbop lesson****. **The Korean system of using your hands as two columns of an abacus. Nice demonstration of the basics.

**Chisenbop on Johnny Carson**. A young chisenbop expert impresses Johnny Carson with adding numbers on her hands.

**Finger multiplication** — on Mathologer. How to multiply numbers between 6 and 10 on your fingers. And this being Mathologer, how to extend the technique further, into negative fingers and beyond. By the droll mathematician/juggler/ambigrammist Burkard Polster

**How high can you count on your fingers?** Lesson by James Tanton, wonderfully animated by TED ED. Covers the same topics as my Math Monday.

**Vi Hart counts in binary**. The mathemusician Vi Hart adds stylish hand dancing to counting in binary on your hands. Makes counting look cool.