The Prestidigitation Approximation

"The Prestidigitation Approximation" is the eighteenth episode of the fourth season of the   The Big Bang Theory. This episode first aired on March 10, 2011.

Summary
Priya feels threatened by Leonard hanging out with his ex-girlfriend Penny all the time and tells Leonard that he has to cut the cord with her. Meanwhile, Sheldon attempts to figure out Howard's magic trick.

Extended Plot
Leonard and Priya are in bed together at Leonard's place. They discuss the implied in Leonard's attempt in trying out positions from the  and, shortly after, Priya urges him to get  as she claims he has beautiful eyes.

Later, at the cafeteria, Howard offers to show Raj a but Sheldon intervenes and tells him he shouldn't be wasting his time with such trivial matters. Howard performs the trick anyway and impresses both Raj and Sheldon. Although Sheldon the trick, he is still keen to unravel it. Leonard comes in with his new contact lenses which are clearly incompatible with him, and he crashes into several people and furniture.

Back at apartment 4A, Howard impresses Penny with his magic trick as Sheldon watches carefully, apparently still stumped by the. Leonard comes back from shopping for "more grown-up" clothes with Priya and they head for his room. Priya voices her feelings about Leonard hanging out with Penny all the time and asks him to terminate their relationship, and he reluctantly agrees. Meanwhile, Howard continually impresses his friends with the magic trick, and Penny appears to have successfully figured out the magic trick, which further crushes Sheldon's ego.

Leonard and Penny bump into each other in the laundry room, where she "saves" Leonard's new shirt that Priya bought for him, seeing that he was about to ruin it by throwing it into the. She then jokingly says, "What will you do without me?", which makes Leonard feel guilty about the promise he made to Priya, which he knows he must fulfill. He nervously tries using and his theory of  as an  for their current relationship, and tries to hint that he would like to see her less without saying it directly. His obscure method "cutting their ties" confuses Penny, and she leaves the room thinking no different of their friendship. Later, when Priya questions him about whether or not he spoke to Penny about this issue yet, he hastily confirms that he has, hoping that the issue is now settled.

Meanwhile, Sheldon has grown increasingly obsessive with understanding Howard's magic trick, and has even gone as far as hacking into the 's to analyze shuffling patterns and looks into procuring  off of  after wondering if Howard used a.



Later that evening Priya and Leonard are having dinner at the Tandoori Palace, and Priya reveals that she has been offered a job in . Leonard is thrilled at this news and enthusiastically takes her hand. At this moment they're interrupted by a tapping sound, and look up to see Penny smiling and waving at them from behind the window. She then enters the restaurant and makes a scene, mocking Leonard's clothes and appearance before picking food off his plate and drinking out of his glass. This angers Priya, who deduces that Leonard never fulfilled his promise to cut his ties with Penny.

At the cafeteria, Sheldon claims he has solved and improved Howard's magic trick, but it turns out he has d all the cards and used a barcode reader to identify it. Howard feels that Sheldon's execution was pathetic and shows the trick again, but this time it is revealed to the audience that Raj (and Penny) has been playing along with Howard's wild guesses as a mean joke on Sheldon, knowing that he would go nuts trying to figure it out.

Later, Leonard finally musters up the courage to tell the truth to Penny, and it quickly dawns on her that there are complications in their friendship due to Leonard's current relationship with Priya, and she agrees to keep a distance (though it obviously doesn't last). She kisses him and tells him.

Sheldon is depressed that he is unable to solve the magic trick. The busted him for hacking into the Cray supercomputer and trying to buy Uranium-235 over the internet. (Rather than arresting him, the DHS let his mother deal with him, which Sheldon claims is a far worse punishment.) Howard offers to show it again. However, this time Sheldon requests Howard try it on him, and Howard reluctantly agrees. Sheldon isn't "" like Raj is, and with his finely-tuned senses, he will spot Howard's trick as soon as Howard screws up. But with all of his focus on Howard, Sheldon doesn't notice Raj signalling to Howard that Sheldon's card is the. Furiously, Sheldon storms out of the cafeteria as Raj and Howard dissolve into laughter.

Critics

 * The TV Critic: "The card trick plot was fantastic. It was far from the funniest story you will see but for a show that so often tells incomplete stories it was very refreshing to see one written so perfectly...Unfortunately everything that Leonard did made him look like a coward. The fact that he can't bring himself to be honest with Penny does him no favours. He then lies to Priya and pathetically hopes things will work themselves out. Then when Penny does him a favour by figuring out what is really going on and taking it well he almost comes on to her...I don't think the producers of The Big Bang Theory are intentionally making Leonard so un-admirable. But regardless that is what's happening and it makes the show less fun to watch. Otherwise this was pretty good."
 * The A.V. Club gave this episode a B-.
 * IMDb user reviews

Trivia

 * Leonard tried to use contact lenses in the 7th grade.
 * Leonard was his school's president.
 * Leonard has two Star Trek uniforms, everyday and dress. One appears to be a beige wraparound tunic and the other a green-gold shirt, both command division colors. In "The White Asparagus Triangulation", Sheldon refers to Leonard as Kirk in his "landing party". Raj has a uniform, which Priya and her family are embarrassed to know. Leonard asks, "Hypothetically, if I had access to a Lieutenant Uhura uniform, would you wear it?" She finally wears the uniform for Leonard in "The Roommate Transmogrification".
 * Leonard can hear Penny's toilet flush from his apartment.
 * This is the first time we see the Tandoori Palace which has been referenced in previous episodes.
 * Sheldon's board displays the number of ways (52! or approx. 8 x 1067) to shuffle a deck of playing cards.
 * Raj's birthday is October 6th.
 * A poster for is visible in the cafeteria.
 * This isn't the first time Sheldon has been busted by the government. In "The Luminous Fish Effect", Sheldon's mom said that, as a boy, Sheldon tried to build a in the, but was foiled when two men from the government showed up and told him that his project was illegal.
 * Howard is not always doing the same card trick each time he demonstrates it.
 * Penny bids a sad farewell to Leonard, though it doesn't last.
 * Despite always being depicted as wearing boxer shorts in all his underwear scenes, this is the one and only time Leonard is mentioned to wear briefs. (mentioned by Sheldon during the infrared camera scene)

Quotes

 * Penny: (to Howard) Y'know, I think I know how you did the card trick.
 * Sheldon: Oh, please. If I don't know, you don't know. That's.
 * Penny: C'mere. (whispers in Howard's ear)
 * Howard: You're right.
 * Penny: Not too bad for someone who doesn't know what "axiomatic" means.
 * Sheldon: Drat.


 * Sheldon: Howard, if I may interject here with a piece of friendly advice. Is working on magic tricks really how you want to spend your time? Granted, you’re just an engineer, but that doesn't mean you might not someday build a geegaw or a thingamabob that may get you a thank you in someone else’s Nobel Prize acceptance speech.


 * Penny: Oh, for god’s sake, Leonard, this is about Priya, isn't it? She doesn't want me hanging out with you.
 * Leonard: Yes. There, I said it.
 * Penny: Okay, look, I happen to like your girlfriend.
 * Leonard: And she likes you.
 * Penny: No, she doesn't.
 * Leonard: Not really, no.
 * Penny: It doesn't matter. Look, I promise from now on I will keep my distance from you.
 * Leonard: Well, now, hold on. What kind of distance are we talking about? Because we are neighbors. I mean, I can hear the toilet flush in your apartment.
 * Penny: You can hear my toilet flush?
 * Leonard: I don’t listen for it, but it’s nice to know everything’s okay with your plumbing. The building’s plumbing.
 * Penny: Leonard, I get it. You’re in a new relationship now. And I’m happy for you. So why don’t we just shake hands and part friends?
 * Leonard: Well, now hold on, how about this? How about we still hang out, but on the down-low?
 * Penny: Are you really that kind of guy?
 * Leonard: No. I actually felt kinda silly just saying on the down-low.
 * Penny: {sadly} Good-bye, Leonard.