多数程序设计语言处理整数的能力是有限的，如C语言中，int 类型数据范围是-32768—32767。实际问题的处理过程中往往涉及大整数的运算，如RSA加密算法要求至少64bit的整数，设计算法实现大整数的加减运算（选做乘除运算）。-Most integer programming language to deal with a limited capacity, such as the C language, int scope of the type of data is-32768-32767. Practical problems in the process often involves large integer arithmetic, such as the RSA encryption algorithm requires at least 64bit integer, design algorithm to achieve big integer addition and subtraction calculations (the election to do multiplication and division operations).