"Pilot" is the first episode of the American television show Numbers. Based on a real-life serial rape case, "Pilot" features two brothers, an agent with the Federal Bureau of Investigation (FBI) and a mathematics professor at a Southern California university, using their individual skills to capture a serial rapist who has begun to kill his victims. "Pilot" also introduces the theme of mathematics being used to solve crimes.

Written by series creators Cheryl Heuton and Nicolas Falacci, the episode was filmed twice, once in Boston, Massachusetts and once in Los Angeles, California, with two different casts using two somewhat different scripts. The test audience could not believe that the three men who portrayed the family could be related to each other, so the producers made cast changes to the family. They also made several changes to the rest of the cast to accommodate the changes in the script. Heuton and Falacci changed the script to focus on the brothers' relationship with each other. When filming finished, CBS picked up the episode and the series three weeks later.

"Pilot" first aired in the United States on January 23, 2005. The episode received mixed reviews. Mathematicians and students at California Institute of Technology enjoyed the episode and were impressed with the mathematics in it. In contrast, television critics felt as though the episode's plot about a serial rapist was unoriginal, although one critic called the math boring.

FBI Special Agents Don Eppes (Rob Morrow), Terry Lake (Sabrina Lloyd) and David Sinclair (Alimi Ballard) investigate a serial rapist who has begun killing his victims. With the twelfth victim, Karen Silber (Kate Norby), changing her story again and the thirteenth victim's car missing, Don runs out of viable leads. Taking a map and a case file with him, Don goes to his childhood home, owned by his father Alan Eppes (Judd Hirsch), to take a shower. Don's younger brother, Dr. Charlie Eppes (David Krumholtz) of CalSci's mathematics department, finds and studies the map which Don lays on the dining room table. As Don prepares to return to the office, Charlie tries to talk Don into letting him help with the investigation and is inspired by the pattern of drops emanating from the family's sprinkler. He tells Don that he can use a mathematical model to find the neighborhood where the rapist resides. Skeptical, Don agrees to let Charlie assist him in the investigation.

Charlie develops the model needed to find the rapist and refines it with graduate student Amita Ramanujan's (Navi Rawat) assistance. Charlie's model yields what he calls a "hot zone", an area in which the suspect probably lives. As the case progresses, Silber is found dead in her house. Don and his team resort to comparing DNA samples of men who live in the hot zone to samples of the rapist/killer. Using statistical analysis, Charlie deduces that Silber lied about where her rape took place. After Don learns from Silber's colleagues where Silber was raped, Charlie refines his equation, which yields a smaller area within the original hot zone. DNA, however, clears everyone in the original hot zone. As a result, Assistant Director in Charge (ADIC) Walter Merrick (Anthony Heald) pulls Don and his team from the investigation. At the same time, Dr. Larry Fleinhardt (Peter MacNicol), Charlie's colleague and friend, encourages Charlie to make his equation "less elegant" and to evaluate the worth of his consultation work.

Back at the Eppes house, Charlie and Don discuss what went wrong. Alan is confident that the math is correct. Don tells Charlie that if Charlie ran his model on Don, the model will not show Don at his apartment. Instead, it would zone in on his office, where he spends most of his time. Charlie then realizes that he needs to modify his model to identify two hot zones, one where the suspect possibly resides and one where he possibly works. Using the new equation and a list of potential suspects who work in the new hot zone, Don, Terry, and David confront the suspect and find his latest victim, who is still alive. After Don kills the suspect in a hostage situation, he calls Charlie down to the crime scene to tell Charlie that the suspect lived in the original hot zone but moved three weeks earlier. This revelation proves that Charlie's models are correct.

Two pilots were filmed. Fascinated by mathematicians, creators Cheryl Heuton and Nicolas Falacci decided to create a show about one. With the encouragement of CBS development executives, they wrote several pilots revolving around mathematicians and scientists, including the pilot for Numb3rs, over the course of 14 years. Knowing that mathematics would not be readily accepted by the general public on its own, Heuton and Falacci in 2003 decided to use the police procedural format to facilitate the acceptance. When Falacci and Heuton pitched the pilot, CBS agreed to produce it about halfway through their presentation.

Although they had considered several story ideas, Heuton and Falacci wanted to feature a case in which math was used to solve a traditional type of crime. They decided to base the episode on a real-life serial rapist case in which police asked Dr. Kim Rossmo to assist them in the investigation. In 1998, Rossmo, then with the Vancouver Police Department, was called in to help Lafayette, Louisiana, police investigator McCullan Gallien find the South Side Rapist. Rossmo and Gallien visited the crime scenes, and Rossmo used criminal geographic targeting, a mathematical model used to find the area in which the suspect would most likely reside. Together, Rossmo and Gallien developed a map indicating the most likely location of the rapist's residence. After DNA cleared everyone living in the area, Gallien learned that a sheriff's deputy in a neighboring department, Randy Comeaux, was a potential suspect. He had lived in the area during the time frame of the rapes but moved to a residence in the neighboring jurisdiction some time later. DNA on a cigarette butt left by Comeaux confirmed that he was the rapist, and Comeaux was arrested.