```
class Solution(object):
def multiply(self, num1, num2):
"""
:type num1: str
:type num2: str
:rtype: str
"""
res = 0
for i in num1:
tmp = 0
for j in num2:
tmp = tmp*10 + int(i)*int(j)
res = res*10 + tmp
return str(res)
```