Risk Runners Presents

Street Math

Risk assessment and estimation techniques — taught not in boardrooms but on street corners, in dive bars, and across kitchen tables.

ISO 31010 • Street-Fighting Mathematics
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Math doesn't need a PowerPoint.

Every technique in ISO 31010 — from Bow Tie Analysis to Markov Chains — was built to help people make better decisions under uncertainty. And every tool in Street-Fighting Mathematics — from dimensional analysis to pictorial proofs — was built to cut through complex problems with educated guessing and opportunistic thinking.

Street Math puts them both on the pavement. Each screenplay drops a real technique into an everyday scenario — a bouncer working the door, a mechanic sizing up a bad engine, a food cart vendor estimating crowd size. The math is real. The characters just speak it differently.

Two traditions. Sixteen stories. All street-level.

ISO 31010 Screenplays

Ten risk assessment techniques through storytelling. Click any card to read the full 10-page screenplay.

B.4.2 — Bow Tie Analysis
The Bouncer's Blueprint
A veteran bouncer explains club security to a rookie using bow tie analysis — mapping threats on the left, consequences on the right, and the bar brawl sitting in the middle. Preventative controls, reactive controls, and the escalation factors that break them.
10 PAGES Read →
B.9.3 — Decision Tree Analysis
The Hustler's Gambit
A street hustler maps out whether to pay off a supplier or dodge them — decision nodes, chance nodes, expected values, and the sensitivity analysis that proves the answer is robust even when the estimates are wrong.
10 PAGES Read →
B.5.10 — Monte Carlo Simulation
The Mechanic's Odds
A shady mechanic runs 100 mental simulations on a customer's engine — random variables for part wear, driving habits, and weather — to show why the "quick fix" has an 86% chance of catastrophic failure.
10 PAGES Read →
B.9.4 — Game Theory
The Roommate's Dilemma
Two roommates face the Prisoner's Dilemma when their landlord offers a deal to whoever snitches first. Payoff matrices, Nash Equilibrium, Tit for Tat, and the commitment device that changes the game entirely.
10 PAGES Read →
B.4.4 — Layers of Protection Analysis
The Heist Planner's Calculus
A meticulous heist planner breaks down a vault's independent protection layers — cameras, guards, biometrics, pressure alarms — calculating the probability of failure on demand for each to determine if the job's risk is tolerable.
10 PAGES Read →
B.3.3 — Ishikawa (Fishbone) Analysis
The Food Truck Meltdown
A food truck owner dissects a ruined lunch rush using the 6Ms — Methods, Machinery, Materials, Manpower, Measurement, and Management — tracing eleven causes back to three root failures.
10 PAGES Read →
B.8.4 — Pareto Charts
The Bartender's 80/20
A veteran bartender teaches a rookie that 80% of their revenue loss comes from just 20% of the causes — and why fixing the bathroom lock instead of slow service is the most expensive mistake in the business.
10 PAGES Read →
B.6.2 — Cross Impact Analysis
The Bookie's Web
A seasoned bookie explains how a star player's sprained ankle doesn't just change the game odds — it shifts the conditional probabilities of every connected prop bet. The money isn't in the obvious line; it's in the web.
10 PAGES Read →
B.9.2 — Cost/Benefit Analysis
The Loan Shark's Lesson
A loan shark walks a borrower through Net Present Value — showing how a "small" $50 weekly payment is actually a 1,160% annual rate, and why the credit union two blocks away is the rational choice.
10 PAGES Read →
B.5.9 — Markov Analysis
The Busker's Calculus
A subway saxophone player calculates transition probabilities between Good, Fair, and Failed train cars — building a Markov chain to figure out when to move, when to stay, and how long before transit police end the session.
10 PAGES Read →

Street-Fighting Mathematics

Six tools from Sanjoy Mahajan's Street-Fighting Mathematics — dimensional analysis, easy cases, lumping, pictorial proofs, successive approximation, and analogy. The art of educated guessing, taught by characters who don't have time for exact solutions.

The Estimation Toolbox

Six problem-solving weapons disguised as screenplays. Click any card to read.

Ch. 1 — Dimensional Analysis
The Vendor's Conversion
A street food vendor debunks a city council comparison between his annual revenue and a corporation's net worth — proving the argument is nonsense because it compares a flow to a stock. Then he estimates the fall damage on a dropped crate using nothing but units.
10 PAGES Read →
Ch. 2 — Easy Cases
The Pool Shark's Limit
A pool shark tests every angle formula by checking what happens at the extremes — zero, infinity, and the one case she can calculate in her head. If a formula fails the easy case, it's wrong, no matter how fancy the algebra looks.
10 PAGES Read →
Ch. 3 — Lumping
The Courier's Shortcut
A bike courier estimates delivery times by lumping complex routes into simple approximations — replacing curvy integrals with rectangles, turning differential equations into algebra, and predicting a pendulum's swing without solving anything exactly.
10 PAGES Read →
Ch. 4 — Pictorial Proofs
The Graffiti Artist's Geometry
A graffiti artist proves mathematical truths by drawing them — stacking odd numbers into squares, splitting rectangles to show why the geometric mean never beats the arithmetic mean, and sketching logarithms as areas under curves.
10 PAGES Read →
Ch. 5 — Taking Out the Big Part
The Bookie's Edge
A retired bookie shows how to multiply large numbers by splitting them into "one" and "few" — extracting the dominant term first, then adding fractional corrections. When the big part is handled, the rest is just noise.
10 PAGES Read →
Ch. 6 — Analogy
The Mechanic's Transfer
An old mechanic solves problems he's never seen by finding ones he has — mapping electrical circuits to plumbing, 2D geometry to 3D, and discrete sums to continuous integrals. If you can solve one, you've solved the other.
10 PAGES Read →