Numb3rs: Watch Episodes Online

Season 4 

401 Trust Metric

After the events of "The Janus List," Colby escapes from custody. Don and the team go after him, but everything may not be as it seems.

Mathematics used: Trust metric, Set covering deployment, Heuristics, Illumination problem

402 Hollywood Homicide

An actor on his way to stardom finds himself in the middle of a murder investigation when a young woman is murdered in his house.

Mathematics used: Snell's law, Archimedes' principle, game theory

403 Velocity

When a car crashes into a busy coffee shop, the team discovers the fatal act might not have been an accident.

Mathematics used: Angular momentum, Centripetal force, Conservation laws, Newton's laws of motion

404 Thirteen

Don, Charlie, and the team attempt to stop a serial killer who is seemingly obsessed with people resembling Biblical figures.

Mathematics used: Fibonacci coding, Numerology, Hebrew numerology

405 Robin Hood

Robberies the storybook hero would have been proud to claim plague Don and Charlie as they attempt to catch a do-good thief who is donating his spoils to charity.

Mathematics used: Listing's law, Projectile motion, Dating system

406 In Security

Don feels responsible for a life lost. The victim was in the Witness Protection Program, but she wasn't the only one keeping secrets...what is Don hiding?

Mathematics used: Regression Analysis

407 Primacy

When a man is found dead, the team enters the world of alternate reality gaming. However, their investigation leads to a danger for a loved one.

Mathematics used: Evolutionary algorithm

408 Tabu

When a wealthy heiress is kidnapped, Don and the team race against the clock in hopes to find her. However, the motivations behind her disappearance aren't what they seem.

Mathematics used: Tabu search, Minimax, Bayesian priors