Introduction - If you have any usage issues, please Google them yourself
(1) The input digits of the additions and subtractions and the additions and subtractions are 1-4 digits;
(2) The additive result shows that the carry output display (i.e. 5-bit output) should be considered.
(3) Attention should be paid to the processing of keyboard input other than "0"-"9", "+" and "=";
(4) Attention should be paid to decimal processing of the additive results.
(5) When the additive and the additive are input, the number displayed on the display should be the same as that input by the usual calculator, that is, every number input, the original number displayed should move to the left;
(6) Accumulative function can be completed.