When I compile the Python code below, I get

IndentationError: unindent does not match any outer indentation level

```
import sys
def Factorial(n): # Return factorial
result = 1
for i in range (1,n):
result = result * i
print "factorial is ",result
return result
```

Why?

Other posters are probably correct…there might be spaces mixed in with your tabs. Try doing a search & replace to replace all tabs with a few spaces.

Try this:

import sys

def Factorial(n): # return factorial

result = 1

for i in range (1,n):

result = result * i

print “factorial is “,result

return result

print Factorial(10)