大数相乘基本算法，相当于模拟手算。使用GMP生成指定数位的01串大数，将生成的01串用char型截取，运算中其实是以一次取4位进行运算。相当于16进制运算。-Multiplication of large numbers of basic algorithms, equivalent to simulate hand count. GMP is generated using the specified digit string of 01 large numbers, will generate a 01 string with the char-type interception operations are actually carried out is a time to take four operations. Is equivalent to 16 hexadecimal operations.