Sara Lin

Background

I did my undergraduate degree at McMaster University (BSc Mathematics & Statistics, 2019) and then an MSc in applied mathematics at the University of Toronto, finishing in 2021. My thesis was on numerical methods for stiff ordinary differential equations — the kind of problem that comes up in chemical kinetics, where some quantities change millions of times faster than others and the obvious solver collapses.

Through both degrees I worked as a teaching assistant for the standard calculus sequence (single-variable, multivariable, vector calculus), which is where I learned that almost every wrong answer in a calculus class comes from forgetting the chain rule, and that the limit definition is worth doing once even though no one ever uses it again.

After my MSc I spent two years as a quantitative analyst at a small trading firm and then went back to writing about maths, which is what I had wanted to do all along. I joined Daniel on Maths Solver in late 2025.

What I write about

On this site I cover calculus and the parts of word-problem solving that overlap with it — rates of change, optimisation, area and volume by integration, and the basic differential equations that show up in introductory physics. The pieces are pitched at a student in their first calculus course, whether that is AP Calculus AB/BC, A-Level Further Maths, or first-year university single-variable calculus.

How to reach me

Best route is the contact form or [email protected]. If you find an error or have a clearer way of explaining something, please write — I’d much rather hear it from you than have a confused student stuck on the article version.

Articles by Sara

• Derivatives, properly explained

  19 min read · April 2026