笨办法学Python3 习题21和习题22

基于Pyhton3.6 习题21 def add(a, b): print(ADDING %d + %d % (a, b)) return a + b def subtract(a, b): print(SUBTARACTING %d - %d % (a, b)) return a - b def multiply(a,b): print(MULTIPLYING %d * %d %(a,b)) return a * b def divide(a, b): print(DIVIDING %d / %d %(a, b))