Popup Calc is a handy calculator app for Android that allows you to perform quick calculations while browsing the web or taking notes. It is designed to be unobtrusive, with a small window that can be moved and resized to avoid getting in the way of other apps. Despite its small size, the app displays calculations with digit grouping for easy readability.

One of the app's standout features is its ability to display the full result of calculations that exceed the window space. By clicking on the result, you can view all digits in a separate screen, which can be scrolled left or right for complete visibility. Additionally, long-pressing the result allows you to copy it to the clipboard for easy pasting. The app also includes an all-clear button that can be activated by long-pressing the back arrow, and a zoom mode that can be activated by long-pressing the plus button and adjusting the window size by dragging.