小型计算器，功能还算齐全，应付小计算足够，还有小数点功能-Small calculator function fairly complete enough to cope with small calculation, decimal point function

实现计算机上面的计算器功能并且满足小数点一及各个符号的功能-Calculator to achieve the above functions of the computer and meet the needs of a decimal point and the functions of the various symbols