Frequently Asked Questions

     This one is easy: Yes. Our materials are free and will remain as such in the future. 

     We opted for the slender vertical page because it seems to be well-suited for the rapid succession of text and equations that constitutes most of our quiz patterns. Also, a slender page layout is nicely compatible with the vertical browsing model used in most desktop and tablet PDF viewers. 

     Absolutely. Use the contact form or email us at and we’ll consider your suggestion as a potential subject in one of our future quizzes or blog posts. 

     Some of our problem solutions may in fact be debatable, or there may exist alternative solution techniques that lead to a correct answer more rapidly or more efficiently than the approach adopted in one of our materials. Students are very much encouraged to send alternative solutions or other kinds of feedback to; if a suggested solution turns out to be better than ours, we’ll readily update the PDF and reference the student who proposed the new solution at the end of the document.

     Yes. In addition to USD, we also accept donations in Euro, British Pound, Indian Rupee, and Brazilian Real. You can choose your preferred currency in the first step of the donation form. The GiveWP donation plugin automatically converts the dollar amounts to the currency you choose, with the exchange rate valid for that day.  

     We apologize for the inconvenience. You can reach us in the contact form page or directly in the email

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