4-Digit Arithmetic iOS App

I need a straightforward iOS application, built in Swift (SwiftUI is fine), that accepts fourteen 4-digit numbers entered manually through an on-screen keypad and can apply several modifications to each 4 digit number using addition, subtraction, and other basic high school mathematical methods... (Budget: $30 - $250 USD, Jobs: App Design, App Development, iOS Development, iPhone, Mobile App Development, Mobile Development, Objective C, Swift, User Interface / IA, Xcode)