Author's Notes: Snape finally does some interesting mathematical calculations in this chapter, hence the title.

Disclaimer: J.K. Rowling owns all Harry Potter characters and settings.

Chapter Nine: Interesting Maths

When the last day of term finally arrived, and the students who were going home had been safely deposited on the Hogwarts Express, Snape breathed a sigh of relief. A couple of weeks away from that girl, finally.

Later that evening, Snape sat in the staffroom, attempting to read through some essays his first year potions classes had handed up. As usual, most of them were not worth the parchment they were written on. There were one or two exceptions – most notably that Winterbourne brat's one. Snape found himself torn between grudging respect and complete loathing for the girl. She was easily the most gifted student in his potions class in her year. Sometimes Snape wondered how Claudia would feel if she could have known that her daughter would succeed so easily, where she herself struggled. Potions had been her Achilles heel at Hogwarts, standing in between her and her future career as an Auror, or at least that is how she felt. She had scraped an E in her OWL and Slughorn had accepted her into his NEWT class, but the first day back in their sixth year Professor Slughorn had approached him.

"Severus! Welcome back!" Slughorn exclaimed, shaking the tall, pale boy's hand.

"Professor," Snape greeted in return.

"I wonder Severus, if I may have a word?" Professor Slughorn asked.

"Of course," Snape replied.

"You see Severus, I have a student, you must know her – Claudia Winterbourne," Professor Slughorn began.

Snape nodded, an image of a tall smiling blonde Gryffindor girl forming in his mind.

"She worked very hard for her OWLs and did quite well, but she's worried that she may find it difficult to keep up with the pace of the NEWT class. She wants to do well because she would like to train as an Auror when she leaves Hogwarts. I was wondering Severus, as long as it doesn't interfere with your own studies of course, if you would mind helping her out a little."

"Me?" Snape asked, surprised at this request.

"You are one of my best students Severus," Slughorn replied.

Snape felt gratified to hear that Slughorn thought highly of him, but he still could not see why the Professor had selected him to help this Winterbourne girl.

"What about Lily Evans? She's a Gryffindor so she probably knows Claudia Winterbourne better than I do," Snape said.


"Ah yes, dear Lily! She has a lot on her plate this year Severus, being a prefect and all. I don't want to over-burden her. I would be very grateful if you could accommodate me Severus."

Snape sighed. He didn't particularly like the idea of having some silly Gryffindor girl tagging along with him during Potions, but Slughorn seemed to have his heart set on the idea.

"Very well," Snape answered.

"Excellent! I won't forget this Severus!" Slughorn answered.

Snape glared at the roll of parchment in his hands, containing Ellie's essay, and pushed it aside. He would look at it later. He picked up another essay and attempted to mark it.

Professor McGonagall and Professor Flitwick were chattering in the corner, making it hard for him to concentrate. He caught a word however, that pulled his attention away from the essay completely. Winterbourne.

"Young Miss Winterbourne is coming along very well with her charms lessons. Of course, I shouldn't be surprised. Her mother excelled at charms!" Professor Flitwick exclaimed.

"Yes indeed," Professor McGonagall replied. "She's doing well in my lessons too. I remember her mother well. Such a pity she never got to take her NEWTs. She wanted to be an Auror. She certainly had the brains for it. Such a waste of a young life," said Professor McGonagall, sighing. Professor Flitwick gave her a knowing nod. Snape's ears pricked up at the last thing Professor McGonagall had said:

"Such a waste of a young life."

That sounded like Claudia had died when she was younger than Snape had assumed. What did McGonagall mean also about Claudia never getting to take her NEWTs? Certainly, Claudia's father had pulled her out of Hogwarts after the first term of their sixth year but, supposedly, she was going to be home-schooled and would still be able to sit the NEWT exams. Snape cleared his throat, hoping to get Professor McGonagall's attention. It worked; both Professor McGonagall and Professor Flitwick looked in his direction.

"Is that Eleanora Winterbourne I heard you talking about?" Snape began.

"Yes it is," Professor McGonagall replied. A thought suddenly seemed to strike her.

"Of course you knew her mother Severus. Claudia Winterbourne was in your year if I'm not mistaken," Professor McGonagall added.

"Yes she was," Snape said, sounding casual but inwardly urging Professor McGonagall to continue.

"Professor Flitwick and I were just saying what an awful tragedy it was, her dying so young. She had such a great future in front of her," Professor McGonagall said, a sad note detectable in her tone.

"Oh really? I hadn't heard that she died," Snape said.

"Oh my! Well yes of course, she left Hogwarts in the middle of your sixth year. Yes, she died the following July. So tragic," Professor McGonagall said.

Snape frowned. Died the following July? That couldn't be right.

"Surely you're not saying she died seven months after leaving Hogwarts?" Snape said at last, expecting Professor McGonagall to correct him and tell him it was the July after that – one year and seven months after her departure from Hogwarts.

"That's exactly what I'm saying Severus. Poor dear. Didn't even make it to her seventeenth birthday," Professor McGonagall replied, shaking her head.

"But… the child…" Snape began, confused.

"Yes well, I don't think it would be right to pass judgement on the poor girl, considering she died so soon after having young Eleanora," said Professor McGonagall, standing up.

"Now, I must get back to my marking. I shall see you both at dinner," she said, inclining her head to both Snape and Professor Flitwick. Professor Flitwick gave a nod in response and then picked up a piece of parchment that had been resting on his lap and began to study it. Snape however had not heard Professor McGonagall's last sentence at all. He was busy furiously counting back the years.

Of course! Why had he not realised it before. He knew the brat must be eleven to be starting at Hogwarts. He had only left Hogwarts as a student ten years ago. Of course that meant that she was born at least a year before he left Hogwarts. What on earth did this mean though? If Claudia had given birth to that girl seven months after leaving Hogwarts then that meant…

As the truth dawned on him, Snape could have been knocked over by even tiny Professor Flitwick. He sat frozen in his chair, horror-struck. He mouth was gaping and his eyes were bulging. That child, that dratted child was… she must be… his daughter.