刚开始学习python编程，困在代码的某个部分？

Question

ShirtNumber = input('How many shirts would you like to order?')

if ShirtNumber >= '12':
    Discount = '0.70'
    Shipping = '0'
elif ShirtNumber >= '6':
    Discount = '0.80'
    Shipping = '8.99'
elif ShirtNumber >= '3':
    Discount = '0.90'
    Shipping = '8.99'

TotalCost = (ShirtNumber * Discount) * 12.99 + Shipping


print('Your total cost comes out to:$ ', TotalCost)

错误是：

TotalCost = (ShirtNumber * Discount) * 12.99 + Shipping
TypeError: can't multiply sequence by non-int of type 'str'

我刚开始编程，所以我还没有完全理解，这只是我的第一个任务。我复习了笔记，似乎不明白自己做错了什么。你知道吗

该计划是基于订购衬衫与较大的数字是订购折扣。如果您有任何建议，将不胜感激。你知道吗

Answer 1

ShirtNumber是一个字符串，不能在两个字符串之间进行数学运算。您可能需要先将其转换为int：

ShirtNumber = int(input('How many shirts would you like to order?'))

类似的，代码中的每个数字都应该是数字，没有引号，比如

if ShirtNumber >= 12:
    Discount = 0.70
    Shipping = 0