Friendly Calculator

Besides of having a nice design the calculator has also the following abilities:
- Auto Complete (for example if the user types: 45sin(90) it inserts the "*" sign between 45 and sin(90)).
- Error Detection and marking the error position with red color. Once the error symbol is in red color one can just press backspace to delete the bad symbol.
- Presents the Solution Steps (It brakes down a complex expression in multiple steps and shows them in the "Solution Steps" Sliding Drawer). The solution steps are stored in the "Solution Steps" Sliding Drawer after pressing the equal button.
- Ability to copy/paste a mathematical expression on the calculator's screen.
- Memorizes the last 30 changes of the screen expression. The buttons "redo", "undo" can help the user to navigate back and forward through the stored states of the expression.
- Memory Copy/ Memory Paste ability. The memory copy button stores whatever the calculator screen hold. This means that the user can store a number as well as an entire mathematical expression.
- An entire section with most used functions and the switch to change from degree to radians.