Helpful and friendly

I am in middle school. I got this because I wanted to learn more. What I loved about it was the fact that the person who made and updates the app helped me. I had a question about a formula that was not on the app. I sent him an e-mail and within a day he had replied with an answer. The most recent update included the formula that I had asked about. The person e-mailed me and thanked me for the idea, which was very friendly.

DragonMax about Math Formulas - Ref. Guide