Simple Soroban 2.1.2 APK

This application is a simple Japanese abacus (soroban / そろばん). It has a free mode where you can use the abacus freely, and a challenge mode with 4 operations (addition, subtraction, one and two digit multiplication, and division) and 3 difficulty levels (easy, medium, hard) where you must race against the clock to perform calculations.Contains tutorials for:* basic concepts* addition* subtraction* one-digit multiplication* two-digit multiplicationAlso has a custom challenge mode where you can set the number of questions, type of questions and difficulty.(This is just a hobby project I'm doing for fun. This app is free and doesn't have in-app purchases or ads).[PERMISSIONS USAGE]This is a description of how permissions are used in this app.Access Network State / Internet: like most apps and sites, this app sends anonymous statistics (Google Analytics) to help improve the app. The user can opt out from the Settings screen.Vibrate: The application can vibrate the phone to give user feedback. This can be enabled/disabled in the Settings screen.