The Doctor sat on a park bench, watching a young child struggling with her maths homework. She looked at the paper furiously.
He walked over to her. "What's wrong?" he asked her.
"Mummy says that I can't go play until I finish this, and I only gots one question left. What's two plus two?"
He told her his answer and she wrote it down, puzzled. She thought it didn't sound right.
Donna marched over then, finally spotting the Doctor. "There you are!! I've been lookin' all over and you've been nowhere! What've you been doing?"
"Helping... um, what's your name?"
"Lily."
"Helping Lily with her homework," he announced with a grin. He seemed so pleased with himself.
Donna quickly scanned the sheet of paper the girl was holding.
"You can add two and two, but you still only come up with the square route of a fifth of gin. Not helping. Sweetie, two plus two equals four."
"Oh, okay, thank you miss!" Lily ran off to show her Mum that she was done.
"Is it that obvious that I'm single?" Donna asked the Doctor. The Doctor sighed and started walking towards the TARDIS.
"No, seirously! Doctor? Doctor?! DOCTOR?!" She chased after the Doctor, annoyed. She never did get an answer to that question.