## Girls’ Angle Bulletin, Volume 16, Number 2

Volume 16, Number 2 opens with an interview with Professor Ellen Goldstein. Ellen is an Assistant Professor of the Practice of Mathematics at Boston College. She is a graduate of Skidmore College where she double majored in math and dance. She continues to dance today, as a member of Dance Prism. Her interest in communicating mathematics led her to develop and teach a calculus course for underprepared STEM majors.

The cover illustrates exponential growth and shows all the solid pool balls plus a cue ball. Ball number $n$ appears $2^n$ times. What percentage of balls are 8-balls? For more on exponentials, see this issue’s Learn by Doing, which explores why exponentials were created, how they are defined, and how they are extended to all real exponents.

Anna Ma writes about a very topical subject: text generating AIs. It’s getting harder and harder to tell whether a text was written by a human or a computer. How do these AIs work?

Robert Donley continues his series on counting by introducing “up” operators.

Emily and Jasmine continue their romp through the rational numbers. While thinking about the sequence of rational numbers that they learned through social media, they became interested in finding a sequence of nonnegative integers with the property that every nonnegative rational numbers occurs as the ratio of consecutive terms of the sequence exactly once. More precisely, they seek a sequence of nonnegative integers $a_1, a_2, a_3, \dots$ such that for every rational number $r$, there exists a unique positive integer $n$ such that $r = a_n/a_{n+1}$. Can you dream up such a sequence?

We close with some Notes from the Club, which include a wild system of equations in 4 unknowns created by 3 of our members this fall: Beatrice, Eleanor, and Sadie. The three worked this fall with our student mentor Alina. The system is nonlinear and has a unique solution in real numbers. Can you solve it?

We hope you enjoy it!

Finally, a reminder: when you subscribe to the Girls’ Angle Bulletin, you’re not just getting a subscription to a magazine. You are also gaining access to the Girls’ Angle mentors.  We urge all subscribers and members to write us with your math questions or anything else in the Bulletin or having to do with mathematics in general. We will respond. We want you to get active and do mathematics. Parts of the Bulletin are written to induce you to wonder and respond with more questions. Don’t let those questions fade away and become forgotten. Send them to us!

Also, the Girls’ Angle Bulletin is a venue for students who wish to showcase their mathematical achievements that go above and beyond the curriculum. If you’re a student and have discovered something nifty in math, considering submitting it to the Bulletin.

We continue to encourage people to subscribe to our print version, so we have removed some content from the electronic version.  Subscriptions are a great way to support Girls’ Angle while getting something concrete back in return.  We hope you subscribe!