I want to launch a lightweight Android app that helps teenagers sharpen their calculation speed. The core of the project is a bank of 500 multiple-choice questions covering mixed operations—addition, subtraction, multiplication, and division , square, cube , percentage all shuffled together. There will be also a payment interface.some speed math tricks. Here is what I need delivered: • A clean, tap-friendly Android interface that feels engaging to teens. • All 500 questions stored locally so the app works offline. • Randomised order and answer shuffling each session to keep practice fresh. • A simple timer and score display so users can track both accuracy and speed. • A summary screen that shows total correct answers, average time per question, and a quick restart option. • Exportable source code (Android Studio / Kotlin or Java) along with an installable APK. Acceptance criteria: the APK installs without crashes on recent Android versions, every one of the 500 mixed-operation questions appears at least once in a full cycle, scores calculate correctly, and the timer functions accurately. If you have experience building small educational apps and can keep the interface polished yet minimal, I’ll be happy to work closely with you and provide the full question set in CSV or JSON—whichever you prefer.