The free course
The Trader's Arithmetic
No indicator, pattern or instinct outranks four pieces of arithmetic: expectancy, streak probability, drawdown asymmetry and the cost tax. They decide who survives — and they can be learned in an hour, which is more than most traders ever give them. Every formula here is applied to our own system's real numbers, so you can check the working.
7 min01
Expectancy: The Only Score That Matters
Win rate is the number beginners worship. It is also, alone, completely meaningless.
6 min02The Trade-Off Nobody Escapes
Win rate and reward size are not two dials you can both turn up. They are two ends of one seesaw.
6 min03Losing Streaks Are a Promise
A run of seven straight losses feels like proof the system is broken. Usually it is proof that arithmetic works.
6 min04The Hole Gets Steeper: Drawdown and Ruin
Losses and gains are not mirror images. The deeper the hole, the more the ladder out costs.
6 min05Compounding, Without the Instagram Filter
Compounding is genuinely magical. The magic just runs on a timescale no one selling you a course can monetise.
6 min06The Cost Tax: Arithmetic's Final Word
Your expectancy has a silent partner who takes their cut on every single trade, win or lose.