Multiplication function with recursion in Python

You are trying to call n(m+1) in your elif and else block, since you say n is an integer, this is the problem, you should be calling mult() function recursively sending n and m+1 or m-1 as parameters.

Another issue is that you should convert the result of n - mult(n, m+1) to negative before returning.

Example –

...
    return - (n - mult(n, m+1))
else:
    return n + mult(n, m-1)

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Demo with example changes –

>>> mult(5,-3)
-15
>>> mult(-10,-3)
30
>>> mult(5,3)
15