Simply press the button showing the current angle mode (e.g., `DEG`) in the top row of the basic panel. This will cycle through the available modes: Degrees (DEG), Radians (RAD), and Gradians (GRAD). The active mode is always shown on the display.

`AC` stands for "All Clear." It completely resets the current calculation, clearing both the expression and the result. `CE` stands for "Clear Entry," which only clears the current expression you are typing, leaving the previous result intact.

After you get a result, you can press `M+` to add it to the stored memory or `M-` to subtract it. The `MR` (Memory Recall) button will then insert the current memory value into your expression. Press `MC` (Memory Clear) to reset the stored value back to zero. The 'M' indicator on the screen will light up when a value is stored in memory.