# 代码
def reduceNum(n):
    print("%d = "%n,end="")
    while n not in [1] :
        for index in range(2, n + 1) :
            while n % index == 0:
                n /= index
                if n == 1: 
                    print (index) 
                else : 
                    print ("%d * "%index,end="")
reduceNum(90)
reduceNum(100)
# 输出
90 = 2 * 3 * 3 * 5
100 = 2 * 2 * 5 * 5