The Surd Manipulation, a big bang theory fanfic

Disclaimer: I do not own any of the characters, those rights go to Chuck Lorre and Bill Prady, as well as the rest of the creators of The Big Bang Theory.

*Knock knock knock* "Penny?"

Sheldon urgently needed to talk to his friend. After Howard's launch into space and the accidental hand-hold with Amy, he was feeling tired and confused. Normally, he is aware of every single action he performs throughout the day, so when he unknowingly broke the Relationship Agreement he was taken aback. Unsure about who to turn to, he had settled for Penny, who he distinguished was the most experienced when it came to having a partner.

"Alright Sheldon, I'm coming!" replied a familiar voice from the other side of the wall, and when Penny opened the door she looked as tired as he felt.

"What is it Sheldon? Because if you've come to ask me to drive you to Pottery Barn, then the answer is no."

He tilted his head slightly and his eyebrows knitted together in confusion. "Don't be silly, Pottery Barn day was yesterday. I need to speak to you urgently."

She pressed her hand to her forehead and sighed. "I'm sorry; I just don't want to talk to anybody right now."

He was not going away that easily. "But you have to. It's about me and Amy. I think we might be taking our relationship too quickly and I thought I would come to you about slowing it down. You know, because you usually deter men after the first night you meet them."

Not surprised by his comment, she decided to ignore it and open the door wider. "Fine, you can come in. But no more schemes to stop Amy's advances. Count yourself lucky you don't hear her when she's drunk."

"Oh, I have. And I still don't understand how my physical features remind her of a sexually active praying mantis."

Stepping inside, Sheldon made his way over to her couch and sat at the end nearest to the door. Penny shut the door and headed to the kitchen, taking some freshly made pie out of the refrigerator.

"You want some pie, sweetie? I made it myself."

"Why thank you Penny, I haven't sampled your desserts for a long time."

"That's quite alright. I'll bring ya over a slice."

After fumbling around for a knife, she cut him a piece while wearing gloves (a requirement Sheldon asks for when making food for his consumption) and brought it over. They both smiled as he took the offering and set it down on her coffee table.

"Ah, pie. How I adore both the food substance and the calculator symbol."

Penny lowered herself on to the opposite end of the couch and rested her head on the back.

"How do you always manage to link things to science?"

"It's not science. It's math. And I thought I was here to talk about me."

He had said it like she was stupid, as usual.

"Yeah, about that. We can get to you soon, but there's something I really need to ask you."

"But me and Amy…"

"Shut up Sheldon! I wanted to ask if you could tutor me. Howard going to space has made me think about how he hasn't got a Phd, but he still managed to do the most amazing thing. And with everyone starting to settle down – including you and Amy – I think it's time I made an more of an effort with Leonard. The only problem is; I can't change him into dumbing the conversation down for my benefit. So, I'm going to smarten up for him… and I need you to help me."

Sheldon was impressed, but he thought back to a couple of years ago when she wanted the same thing. "Can't you go back to community college? You hated it the last time I taught you physics."

"I don't want you to teach me physics. I want you to teach me math, in little parts. I don't need to know where Einstein was born and what he did for his twelfth birthday party."

He twisted slightly in his seat to fully face her. "For the record, Albert Einstein was born in Ulm, situated in the Kingdom of Württemberg. Regarding his birthday arrangements, how am I supposed to know? And little parts? Like a 'fact of the day' kind of thing?"

She nodded. "Exactly! Only more than one a day."

"Well ok. As you wish. At least that way we won't get on each other's nerves again."

"Yeah, that and the fact that my brain almost exploded from the information last time."

"An impossibility. The first lesson I want you to learn today is that Pi is not just an after-dinner snack served at your poor excuse of a job. You spell it without the 'E' and it can be used on irrational numbers – decimals that are never ending but have no recurring numbers. Good sources for these types of numbers are square roots and cube roots, and Pi usually comes up when you are finding the area of a circle, in which you times Pi by the squared radius."

He found a scrap piece of paper and a pen on Penny's coffee table and wrote what he meant. The card read 'πr2' and he kept it held up as he carried on. "See? The symbol at the front is Pi and R stands for radius. Remember, you don't square the Pi, so pretend there is a times sign in between the two."

"Wow, I actually understood that! And what are cube roots?"

"Like squared roots, but instead of the little two you replace it with a three. For example, if you cube the number two, then you get the answer eight, because 2x2 is four and 4x2 is eight. If you cube root the number eight, you get two. Two is an irrational number."

Penny was astounded. "Oh my gosh, thank you Sheldon. For once you actually made sense."

He stood up and headed for the door. "You're welcome. Call it Penny's Pi if you want, and maybe it will help you remember."

She followed him and opened the door, her radiant smile beaming up at him. "The dessert or the formula?"

"Well, I meant the formula, but I admit the dessert was quite something. It deserves a personalisation. Goodbye, Penny. We'll talk about Amy's deterrence another time."

"See you later, sweetie pie!" she responded, quietly laughing at her own joke and closing the door behind her. She felt that the information would come in handy, and maybe be a topic for a conversation with Leonard later this evening.

Just as she was sitting back down, her phone vibrated on the table. As she went to pick it up, she saw who it was from. Opening the text, Penny read it aloud:

"Surds use these irrational square and cube roots. If you ever see Leonard write '√5 × √15 = √75 then knowing both of these numbers are not square and in fact square roots you know he got the 75 by doing 15× 5. Keep the 75, and split that into 25 x 3 which also brings you that answer. Put the root symbols around it like this: √25 × √3 and you can square root the 25 but not the three. Your answer would be 5 √3. This is called manipulating a surd."

She nodded in agreement, and then read the final sentence.

"By the way – I heard your pie joke. I'm momentously disappointed."