VB程序设计技巧---计算器,设计一个可以进行四则运算的简单计算器。该计算器除了可以进行加、减、乘、除、求模（取余）等简单的四则运算外，还要求可以进行四则混合连算，并具有符合计算器日常使用习惯的容错纠错功能。-VB programming skills--- calculator, design a simple calculator can perform four operations. In addition to the calculator can add, subtract, multiply, divide, modulo (remainder), such as a simple four operations, it also requires four can be mixed even count, and has daily habits in line calculator tolerant error correction.