As part of Digital Science’s celebrations for Ada Lovelace Day, for the month of October we are running a series of blog posts where inspiring women in STEM are sharing their personal role models. Anyone can get involved and we encourage you to share your role model on social media using the hashtag #MySTEMrolemodel. 

CLCassandra Lee Yieng, majored in mathematics and minored in information engineering at the Chinese University of Hong Kong (CUHK). She wrote the “highly recommended” entry on the Hong Kong Space Museum (East Wing) at the 2011 “Maths in the City” competition hosted by Professor Marcus du Sautoy of the University of Oxford. In spring and summer 2015, she also wrote the content for the new website of the Department of Mathematics at CUHK.

Apart from mathematics, Cassandra enjoys creative writing, composes music, and showcases her artwork on Twitter and Instagram. Never seeing herself as a nerd, she wants to inspire girls to thrive in mathematics and the sciences, while not forgetting that they could still be sentimental too.

Cassandra’s hobbies are very varied. She loves reading tangible books and electronic ones, as well as knitting, but she also loves to travel and play various sports from tennis to archery. In her spare time she keeps learning new things.

For more about Cassandra, visit her website

“Maths is useful,” said my mum as she sent her little girl off to Kumon. An inflight service manager and long-time flight attendant, she had an arts background and was slow with numbers, but she caught a glimpse of a fact others ignored: everything involves mathematics.

Over time, alone most of the time, I came to enjoy the company of books and wanted to be a writer. However, top writers need a solid background in literature, and my secondary school didn’t offer that. We had no plans to change schools, and I kept remembering the many aspiring writers who ended up poor. Hong Kong is the city of money, and Mum, having been through poverty, advised me continually on financial wisdom.

I felt stranded, but I had topped the charts in English and Mathematics for three years in a row. I thought, Since Mum keeps saying it’s useful, why not find out what opportunities mathematics leads to?

The first mathematical topic in the fourth form was quadratic equations—stiffly-looking midgets, they seemed. I Googled “applications of quadratic equations” and found Plus Magazine’s article “101 uses of a quadratic equation: Part II”. I also read Part I as well. I didn’t know that quadratic equations had so many uses, and I visited that website frequently to keep myself updated on the usefulness of mathematics.

As for my stream choice, I picked the science stream straightaway, with advanced mathematics and computer science as electives, even though at that point, I was much better at geography, a subject in which my mother also excelled during her student days for a travel career. (Science students at my school could only pick one of geography and computer science.) At that point, though, my mum could no longer encourage me in mathematics, but I did many fun exercises thanks to Miss Celine Loi, a sterling private maths tutor in Singapore, and the O-Levels there are slightly harder than the equivalent school-leaving examination, the HKCEE, in Hong Kong under the British educational system.

Boys did not just outnumber girls at my university; the ratio of boy to girl students in mathematics ranged from 8:2 to 9:1. Although I expected to be in the minority, I didn’t realise the minority was that small! However, I am indebted to several women postgraduates who helped me, some were tutors and one was an alumna.

I must thank my linear algebra tutor, Jessey Lin, for not giving up on me even though I struggled to understand the symbolic “new maths”, which was unlike the computations I coped with in school.


Eventually, when the time came for me to transfer out of a first major in chemistry, I also chose mathematics over English, and I did quite well at first. In particular another female tutor, Shiping Wang, helped me understand probabilistic distributions, something which stumped me during maths programming class.

However, my grades slumped and I was advised against a research degree, until I met Mandy Man-wai Cheung, a PhD candidate at the University of Cambridge and speaker at a public mathematics lecture for secondary students gifted in mathematics. A top student herself, she researches on abstract algebra and algebraic geometry, yet the overwhelming male dominance in those mathematical branches did not intimidate her. “I once taught a geometry class, all boys,” she said during the talk. She still speaks up on mathematical contributions by women—“maintain the fighting spirit” as an academic and as a woman.

Apart from my essay on Emmy Noether, one of the first few female mathematicians who could be considered algebraic geometers, I told the mathematics department I wanted to write about female students, past and present, for their upcoming newsletter, and we are working together on this. Meanwhile, my grades have gone up.

I have a note on computing—it turned out that I also did very well in it. I didn’t want my interest in computing to overtake my mathematical endeavours, so I took up a minor in information engineering instead. Engineering is another field full of men, but I am happy to be inspired by women like Qianmei Yang, a tutor in communication networks.

None of this would have been possible without my mum, but I felt a certain disconnect. So one day I asked her, “If you said mathematics was useful, why didn’t you study it? Your school had the science stream.”

She thought for a moment, and said, “π.”

“That’s a simple concept,” I said. “It’s the ratio of a circle’s circumference to its diameter. What’s wrong with that?”

“The teacher in primary school couldn’t explain it. She just chalked the formulas 2πr and πr2 and told us to fend for ourselves memorizing it. I raised my hand, got to confront her and pressed her to explain why the formula was like that. Do you know what she said?”

I shook my head.

“You ask too many questions. Maths is maths, and these are the formulas you must remember.”

“That’s a bad teacher,” I said.

“From then on, I did not like maths any more. But I still needed to use it in grocery shopping and calculating anything money-related. That’s why I told you it was useful.”

But the usefulness of mathematics I learnt, I told her, went far deeper than mere calculation. It forms the heart of modern cryptography, the study of hiding your sensitive information from another. It is used to create smaller computers that run faster. It comes to the rescue when we explore the universe and the quantum world, and new mathematics is being discovered to keep pushing back the frontiers.

Meeting women who share my passion inspire me. It is important for us to stick together, and not be afraid to seek help when needed and to speak up for ourselves.