▍1. cal
程序提示用户输入两个数,然后它将输出这两个数字的和、差、积、商、以及余数,分十进制和十六进制两种格式 (The program prompts the user to enter two numbers, then it will be the output of these two numbers and difference, product, quotient, and the remainder, and decimal and hexadecimal two formats)