再来一个

# -*- coding:UTF-8 -*-
def reduceNum(n):
    print '{}= '.format(n),
    if not isinstance(n,int) or n<=0:
        print '请输入一个正确的数字！'
        exit(0)
    elif n in [1]:
        print '{}'.format(n)
    while n not in [1]:
        for index in xrange(2,n+1):
            if n%index==0:
                n/=index
            if n==1:
                print index
            else:
                print '{} *'.format(index),
            break
reduceNum(90)
reduceNum(100)