This is the "Chrome Desktop" version of the app, meant to work as standalone ("desktop") application (accessible from Chrome App Launcher and working in separate window, not in the browser itself).
Since the calculator is working in separate window, you may want to try different sizes and orientations. The tool will remember it's size and position between restarts (so the next time when you launch the calculator it will open in the same size and position on screen). The app comes with "liquid" layout, so you could resize it to be "tall" or "wide":
The app itself is more or less "unusual". In general, it is standard scientific calculator. The "strange" thing is that when you perform a calculation you can see both sides of the current binary operation. This is little unusual, but gives you more control on the calculations performed. Just remember that unary operations are performed on the second operand, if there are two operands already entered. If you want the whole result to be used as an input for the next operation, press Enter (or tap =) first. Sounds complicated? Here is a step-by-step example: (1) Enter 5 + 5 (2) Click X2 button (3) The result is now 5 + 25; If you want to square the result of the current operation (5+5 in the above example) -- click = first and then the unary operation (X2 in the example).On devices with keyboard you can use the obvious keys: number keys, dot (floating point), +, -, *, /, Enter (=) and BackSpace. The advanced ("scientific") functions are not yet accessible with keyboard shortcuts (but better keyboard support is planned for the next versions).
How to add calculator button to the toolbar?
As you know Chrome apps (like this one) can't add icons to main toolbar. To fix this we made another version of Melanto Calculator, this time as extension (with toolbar icon):