Simple Calculator and Unit Converter Calculator are two free apps developed by SimpleTools.nl for Android 9.0.

The Simple Calculator app has a clear display and large buttons, making calculations easy. The basic functions of the calculator are used to create a simple yet effective app. The app is easy to use and can be downloaded for free from the Play Store.

The Unit Converter Calculator is a fast and free app that can easily convert over 140+ units of measurement. The app is beautifully designed and has a universal interface. It is a powerful conversion calculator that covers popular measurement tools such as length, number, power, speed, temperature, time, weight, area, and energy. The app is easy to use and can also be downloaded for free from the Play Store.