Calculate+4 -simple calculator

I made the concept that, want to use a calculator on a tablet and also want to use a calculator with a simple design.
The buttons are large and easy to touch, and have a simple design. In calculator + 4 we put four calculators on one screen when we turned horizontally.
I think that it is useful in various places if you have to do simultaneous calculation.
[Major features]:
-Simple and easy design
-The button is large and easy to touch
-When turned horizontally, equipped with four calculators can be calculated simultaneously
-For portrait orientation, delete the rightmost value with backspace button
-Percent calculation also possible
-Supports both vertical and horizontal display
-Display comma (,) in every three digits for easy reading of calculation result
Supported Operators:
-Basic operations: +,-, x, ÷,%
-+/- conversion
If you have any comments or suggestions about this app, please contact us anytime