History Series / NUMB3RS

* JackBauerInterrogationTechnique: The episode "Two Daughters" has this technique being pulled on Buck Winters, so that [[spoiler: they can find out where his wife, Crystal Hoyle, has taken the kidnapped Megan]].

-->'''Bureaucrat''': You know, you're a lot like your brother.

* EnhanceButton: A first season episode deconstructs this trope. They are able to "zoom in" on a poor-resolution image, but Charlie and Amita explain that what they're seeing isn't actually information contained in the original image, but rather a predictive tool that extrapolates from the existing data to fill in the missing information as best it can.

** Season 5's "Cover Me" involves Charlie coming up with a convoluted plan to disrupt the supply of a new drug, known as Hawaiian Ice, with the intention of preventing it from being able to become mainstream. While it actually works with regards to that particular drug, Charlie subsequently learns that rather than leading to an overall reduction in drug crime, the lack of this one drug just led to an increase in the trafficking of other drugs. Don tries to convince him that he still made an impact, even if it wasn't exactly what he was hoping for, but Charlie is skeptical.

* FormerTeenRebel: Alan used to be a member of a radical anti-war student group in the 1960's, which causes friction when Don ends up investigating a bombing that ends up linked to the group. The culprit is the son of another ex-member, who turned more conservative after the war ended.

* NeverWinTheLottery: The show had one episode that dealt with people stealing scratchcards in order to decode the relationship between the serial numbers and the distribution system, thereby allowing them to determine where the jackpot-winning ticket would end up so they could buy it. It turns out that the crew were winners of previous lotteries who'd lost all their money due to their inability to manage their spending, with one of them having even managed to blow through a ''15 million dollar'' jackpot, so they formed the group and agreed to split the prize. One character outright references the percentage of lottery winners who end up broke within five years of winning.

* NeverWinTheLottery: The show had one episode that dealt with people using math to predict the appearance of winning scratchcards (due to a printing error, one batch of cards were not randomized properly and yielded a much higher likely hood of winning).

* JurisdictionFriction: {{Zigzagged|Trope}}. Don's FBI crew has a tendency to work and play well with other agencies; they especially have a good relationship with the local cops. However, as shown in "Brutus" and "Finders Keepers", the CIA and NSA are another story.

* GamblersFallacy: Invoked in the pilot, when Don, watching a baseball game with his father, comments that a batter is "due" a big play after going four games without a hit. Charlie is quick to refute this theory, saying that there's "no statistical evidence for a batter being 'due'," but the player does in fact get a big hit. However, it's quickly revealed (to everyone but Charlie himself) that Don is just messing with his brother; what they're watching is not a live game but a tape of a game from the day before, and Don, having read a recap in the paper, already knew what was going to happen, knew that Charlie would react to the fallacy, and intentionally set the whole thing up to yank Charlie's chain.

** Between the lack of night scenes and the timeline of events, "Trust Metric" appears to take place over a single day, though this is never made explicit.

** In ''The OG'', Charlie gets the idea to stop a new drug from hitting the streets by interrupting the supply chain. In the end, his plan succeeds and that particular drug is contained, but other drugs just surge to take its place. Don tries to reassure him that he still made a difference, but Charlie is less than convinced.

--> '''Megan''': Did he say these people weren't real?\\
'''Don''': He said we would never find them. What, do you think he figured it out?\\

** Played with in a later episode. A conspiracy theorist claims that a public figure and his charitable organization aren't on the up-and-up. He turns out to be right, but the implication is that it's pretty much luck and chance; given how many people he thinks are doing something illicit, one of them was bound to end up being actually sleazy. [[note]] He was also right only in the broadest possible sense; the actual crime that was committed bears virtually no resemblance to his theories.[[/note]] The trope is even [[LampshadeHanging Lampshaded]] by Roin.
--> '''Robin''': on the other hand, [=McGill=] may not be so crazy. ({{Beat}}) [[VerbalBackspace Okay, he's crazy]], but that doesn't mean that he's wrong.

*** He goes through one in the very second episode when Don is placed in a life-threatening situation because he followed Charlie's advice:

*** He tries to work himself into a safe space by trying to solve the famously difficult [[https://en.wikipedia.org/wiki/P_versus_NP_problem P vs. NP problem]]. Don isn't happy about this since Charlie buried himself in the exact same problem after their mother got cancer, and it takes a while to coax him out of it.

*** In the former case of Don's stabbing, Charlie actually works though the aftermath in the next episode by studying crime stats leading him to find a SerialKiller operating for over three decades that ''no-one'' even realize to look for.

* SlowElectricity: In one episode, the case involves several reactors being taken down in an attempt to create a cascading failure. The shot of the shutdown when it occurs is basically the same thing as most shows/movies though, but it's a bit more valid than a full electrical failure causing the skyline shutdown sequence.

* CloningBlues: [[spoiler:The "kidnapped" girl in the Hydra episode]].

* MisplacedRetribution: The villain of "Judgement Call" has this as their motivation. [[spoiler: A detective got killed and his killer caught, but though the jury recommended the death penalty, the judge overruled them and gave him life in prison instead. For years after, the cop killer made numerous appeals for retrials, agonizing the detective's widow with every moment that looked like he'd go free. When she finally couldn't take it any more, through her husband's old contacts, she found a hitman to go after the judge's wife, to make him think about "the next criminal he goes easy on".]]