## Girls’ Angle Bulletin, Volume 16, Number 3

We have been incredibly fortunate to have had an interview with a woman in mathematics in every single issue of the Bulletin but one. All of these women are remarkable and have fascinating stories to tell. They’re wonderful role models. In Volume 16, Number 3, we interview Wellesley Professor of Mathematics Megan Kerr. Aside from this interview, Prof. Kerr has been a valued source of advice and has been supportive and helpful to Girls’ Angle in vital ways. Prof. Kerr is also a Wellesley alumna.

The cover is created by Juliette Majid who brilliantly illustrates the mathematical structure that Emily and Jasmine have been unravelling in their latest math adventure. Juliette also designed the cover of Volume 14, Number 6. To understand the meaning of the cover, read the 3rd installment of Romping Through the Rationals where Emily and Jasmine crack the mystery of a sequence they learned about on the internet that supposedly lists every single nonnegative rational number exactly once.

The Emily and Jasmine series aims to show how math is done. By contrast, in school, we are taught what math has been done, and it can be easy to forget that all the math that has been done once did not even exist. Someone had to create it. Professional mathematicians spend much of their time trying to create new math. We can all be creators of new math. As you read Emily and Jasmine, ask yourself if there’s anything they do that you cannot picture yourself doing?

In the same spirit, Addie Summer tells us about her adventure counting domino tilings of a zigzag path in a park. Before reading the whole article, we urge you to read just as far as the statement of the problem she considers, then try to solve the problem yourself. There are many ways to go about solving this problem, and you’ll likely find something different from what Addie does. (And if you do, tell us about it!)

Robert Donley continues his series on counting and partially ordered sets, this time stumbling upon multinomial coefficients and the generalization of Chu-Vandermonde convolution to them.

We also give our take on the oft-asked question, “What is $0^0$?” Often, people will say that it is 1 and explain how this is because $\lim_{x \to 0^+} x^x = 1$. However, it’s important to understand that this is not a proof that $0^0 = 1$. (Likewise, observing that $\lim_{x \to 0^+} x/x = 1$ does not imply that $0/0 = 1$!) Never forget that math is a creation of the human mind. We are the creators of math, and you can be too!

We close with some Notes from the Club where you can find a little-known way to produce the graph of the cosine function by using a sheet of origami paper.

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!