Blame Roxanne and my it's-two-am brain for this one. It's short, but hey. It's two in the morning.

"Hey," Leonard said, smiling at the sight of his girlfriend. "How was your day?"

"Great," she said, kissing him hello. "Let's go to your apartment."

Leonard cocked his head. "Why do you want to go over there?"

"Because." Penny said, grabbing his hand and tugging him toward the door.

"I'm…a little confused," he said, frowning. "Is something wrong?"

"No!" she said, turning around to face him. "Leonard," she said, in a tone that suggested he was silly for even asking. "Nothing's wrong. Why would anything be wrong?" She grabbed both his hands and kissed him lightly. "Don't you worry. About anything. You understand me?"

Leonard was still a little confused, but he nodded. "Absolutely."

She smiled. "Okay." As they reached the door to 4A, Penny fished out her key and unlocked it. Leonard heard her take a deep breath as she let it open and walked inside. When they got into the apartment, she turned him around and wrapped her arms around his neck, kissing him, turning them slightly so he was facing the back wall, where his board was.

When the kiss was over, Penny buried her head into his shoulder, and he smiled fondly, curling his arms around her. His eyes now opened, his eyes fell on his board, no longer wiped clean from this morning, and his eyes widened and he took a step back. He felt Penny tense.

The words Will you marry me? Were written out on the board, in the style of a math problem with many letter variables, with the E in "me" an equals sign, and the question mark next to it being the final unknown.

Leonard stepped back, and she gave him a small smile, her eyes wide. "Do you know the answer?" she whispered.

Leonard leaned in and kissed her, a hand on her face, the other on her back, and when they broke apart – against Penny's wishes – he went over to the board, and added ? = Y E S. The equation wouldn't work out correctly if it was an actual problem, but Leonard wasn't going to bring that up. It was creative, it was a surprise, and that was more than enough. He turned around; she was standing shyly behind him, smiling. "So that's why you wanted me to come over here right away," he said.

"Well, partly," she admitted. "I'd been wanting to do this for a week and you never erased your board. I didn't want to ruin your equations.

Leonard turned around, changed his answer to Hell Yes, and then pulled her back into his arms.