Lily Serna: the division belle

Lily Serna was just five years old when, driving around the city of Jerusalem with her grandfather, she first ran headlong into infinity.

With the old man assisting, she practised her counting. “We reached all the way up to a hundred, and I couldn’t imagine a bigger number,” she recalls. “He told me no matter what number I could think of, there was always a number bigger.”

Young Serna was perplexed, but a seed had been sown. It would grow into a passion, and lead to an unusual career that spans the realms of mathematics and television. With a head for figures, she gathered a cult following as co-compere of a geeky game show called Letters and Numbers. In the world of maths entertainment – “quite a narrow field,” she acknowledges – Serna became a superstar.

When she was eight, her parents moved the family from Jerusalem to Sydney to secure a better education for her and her brother. “Education was very important to them,” she says, and that too took root.

After high school she combined abstract and worldly interests by pursuing maths, finance and international studies at the University of Technology Sydney. A year of that was spent studying in France, and after completing a double degree she decided to continue on with an honours year in maths. “And in the middle of that, I fell into TV.”

The fall began at a maths camp at La Trobe University in Melbourne, where Serna met someone with a connection to Australia’s Special Broadcasting Service. SBS, it transpired, was looking for a woman with pro-level maths to co-host a brain-teasing game show.

Its oddball charm and unashamed nerdery helped Letters and Numbers become a cult hit. Serna herself played no small part in its success; she dazzled audiences with her arithmetical acumen.

“I didn’t have a job at the time, so I thought I might as well go for it. I said to my mum, ‘Imagine if I got this,’ and we both burst out laughing, because it was the most unimaginable thing.” Get the job Serna did.

Letters and Numbers was based on a pair of long-running French and British programs in which contestants competed against in-house experts in games of arithmetic and wordplay. The show was hosted by veteran newsreader Richard Morecroft with two expert sidekicks: the letters were handled by crossword guru David Astle; the numbers by Serna.

Its oddball charm and unashamed nerdery helped Letters and Numbers become a cult hit. Serna herself played no small part in its success: she dazzled audiences with her winning smile and arithmetical acumen, and began to acquire a loyal following of her own. Although Letters and Numbers only ran from 2010 to 2012, reruns still air today.

“My career then split into two,” she says, “and I’ve been on both paths ever since.”

Despite a hectic filming schedule – shooting 450 half-hour episodes over two years – Serna continued her studies part-time. She had won a scholarship to work on an honours project with CSIRO that applied fluid dynamics to marine biology, modelling the movement of pollution in water around Queensland’s Great Barrier Reef. Unsurprisingly, she received top marks.

Lily serna shows off her figures on letters and numbers.

Serna’s twin paths next took her into environmental consulting and touring Australia with fellow part-time TV personalities Adam Liaw (a former lawyer turned chef) and Renee Lim (a doctor) to film a combination food and travel show, Destination Flavour.

In early 2016, Serna got a tip from her brother, who was working as an engineering manager at the fast-growing software company Atlassian, about a job going for someone with her skills.

Atlassian, which in 15 years has gone from garage start-up to multibillion-dollar behemoth, makes software for use by other companies, mainly for managing projects and helping teams collaborate. Serna’s job is to use data to help understand and improve customer experience.

“Companies generate so much data,” she says. “I have all these mathematical techniques and methods that I apply to the data to get a picture of what is going on. Technically, there are a whole host of things I do – hypothesis testing, machine learning, predictive modelling, cluster analysis. The buzzword for this type of work is data science, but basically I do maths.”

It is “a very fun company to work for”, according to Serna. “There are a lot of bright people around to learn from.”

In addition to her day jobs, one of Serna’s aims is to be a role model for women working in maths, where they have historically been underrepresented.

“There are two facts that we have in front of us,” she says, laying out the case. “One, we know that women generally have lower confidence in their maths ability. Two, there have been any number of tests to show that, on average, there is no difference between men and women in mathematical aptitude. This is what we have to work with.

“Historically women were actively discouraged from going into maths and science. That kind of discrimination has a real long-term effect. Although things are improving, it takes a while for that kind of thing to filter out.”

Serna’s personal experiences have been largely positive. “I won’t say I’ve never come across [discrimination], because I have, but I genuinely believe that 99% of people don’t discriminate. And I have a healthy dose of defiance and a charge-on attitude – it’s not something I’ve ever thought is going to stop me.”

Serna appeared in an episode of ABC’s science documentary show, Catalyst. Though, at the time of writing this, the details were still under wraps, she was allowed to say it was about “how we can use maths to make more rigorous decisions”.

Despite already having two highly successful careers, Serna would also like to spread out into other areas.

“I’d love to set up some kind of not-for-profit that helps kids with their maths homework. A lot of studies show that kids who get help or have mentors from earlier on are more likely to enjoy maths.”

“And puzzles,” she adds as an afterthought. “People like puzzles. I’d like to do something else with puzzles.” (She published a book, Lily’s Number Puzzles, in 2012.)

“My problem is that I always have too many ideas. I need to concentrate on a few.”

It’s just like numbers: no matter what you think of, there’s always something bigger.

A pair of lily’s puzzles.

A pair of Lily’s puzzles.


The numbers in the series are obtained by adding 5 to consecutive prime numbers (2, 3, 5, 7, 11, 13). The next prime is 17, so the next number in the sequence is 17 + 5 = 22.


Take the two consonants in the first word and add the last two letters of the second word. POOL + CHOP = PLOP

Please login to favourite this article.