Can't understand the math . Why not 5 ?

Question

https://code.sololearn.com/c3p58qYIstm0/?ref=app

Answer 1

def recur(n):
if n == 0:
return 0
else:
return n + recur(n-1)
print(recur(3))

so let's start

n is 3 so it will return

return 3 + recur(2)

we can find the value of recur(2)

n = 2
return 2 + recur (1)

the above result become

return 3 + 2 + recur(1)

again for recur(1)

return 1 + recur(0)

since recur(0) will be 0 because n==0

the whole thing can be written as

return 3+2+1+0

which is 6

If you want to stop at 5
you can change n==0 to n==1

Answer 2

thanks a lot