This Calculator works as normal type of physical calculator:
2 x 3 + 5 = 6 + 5 = 11
It calculates from left side to right side, so it doesn't calculate multiplication and division prior to plus and minus as you do in usual calculation.
Rounddown is not implemented yet
Sometimes the calculation results are more than calculator's display area, sorry.
Please let me know if any issue such as when the result shows you obviously wrong answer.