Simon Rubinstein-Salzedo is the founder and main teacher at Euler Circle. Simon received his PhD at Stanford University in 2012 under the direction of Akshay Venkatesh in algebraic number theory. He has done research in many areas of mathematics, including number theory, algebraic geometry, combinatorics, game theory, probability, and complex analysis. Before founding Euler Circle, Simon taught mathematics at Stanford University and Dartmouth College.

In addition to his teaching at universities, Simon has been teaching mathematics to advanced middle-school and high-school students for over a decade and is extremely popular among his students. He is currently the lecturer for Program II at the Stanford University Mathematics Camp (SUMaC), where he teaches algebraic topology.  He has worked at The Art of Problem Solving and has taught at many math events and run many math circles in the Bay Area. He is also the coach of the San Francisco Bay Area ARML team, which has won the national championship for the last three years. His greatest claim to fame in life is probably having a factoring trick named after him.

Simon has also successfully directed mathematics research projects for high-school students, leading to three original papers coauthored with students so far, and more projects are currently in progress. His papers can be found on his website. Please contact him at

Outside of mathematics, Simon is also an avid musician, chess player, and calligrapher.

Teaching Assistants

annie chenAnnie Chen is an undergraduate at Stanford University studying mathematics. Her interests include analysis, probability, and combinatorics. She has done research in arithmetic dynamics and probability theory and has written a paper and given a conference presentation on her work. In addition, she has previously tutored many advanced middle and high school students in math. In her free time, Annie enjoys playing tennis and card games.

benhellerBen Heller is an undergraduate at Stanford studying mathematics. His interests range over virtually all branches of math, but has a soft spot for mathematical logic, analysis, and differential topology. He has done research in probability theory and has experience tutoring undergraduates in the Stanford math department’s peer tutoring program. Aside from math, he enjoys tinkering with Linux and listening to music.

nik_castroNik Castro is a junior at Stanford studying mathematics.  His interests include real analysis, probability, algebraic topology, and algebraic number theory.  He has graded for both undergraduate and graduate level courses, and was a counselor at the Stanford University Mathematics Camp.  Outside of math, he enjoys practicing martial arts.

nina_zubrilinaNina Zubrilina is an undergraduate at Stanford studying mathematics. She enjoys combinatorics, analytic number theory, analysis, geometry and anything having to do with sphere packing. She has done research in combinatorics and number theory and has written four papers on her work.

Besides Euler circle, her teaching experience includes being a TA for other math circles, TAing a class in Moscow High School #57, being a counselor and TA in a summer math camp, and giving a series of lectures in the Moscow Branch of the Higher School of Economics.

nitya_maniNitya Mani is an undergraduate studying mathematics at Stanford University. She is excited about problems in algebraic number theory and extremal combinatorics and has done research in both areas. Some current areas she is learning more about include geometric measure theory and local class field theory. In addition to being a teaching assistant at Euler Circle for the past 3 years, Nitya coordinates the student peer tutoring program for the Stanford mathematics department and has graded many Stanford math classes.

ryansmithRyan Smith is a master’s student in computer science at Stanford. His interests are in cryptography, computational complexity theory, and algebraic number theory. He has TA experience at the Stanford University Mathematics Camp as well as the computer science department at Stanford. Outside of math he enjoys reading, musical theater, and games of all kinds.

zoe_himwichZoe Himwich is a math major in her senior year at Stanford. She has been a TA at Euler Circle since Winter 2018. Her other teaching experience includes TA-ing at Stanford Math Circle and grading undergraduate math classes. She has done research in several areas of mathematics, including graph theory, topological quantum field theories, and the mathematics of phylogenetics. When not doing math, Zoe studies English literature and enjoys learning new languages.