Function

Question

# Write a function that accepts three numbers and calculates their product and returns the result.
#declared my variables
n1 = int(input())
n2 = int(input())
n3 = int(input())
def mul_num(a):# define a function
a = n1 * n2 * n3
my_result = a
return my_result
print(mul_num(a))# call a function
Below code is working fine:
a = [2,3,5]
#mul =1
def mul_num(n):
mul=1
for n in a:
mul = mul * n
return mul
print(mul_num(a))
What I did wrong in the first piece of code?

Answer 1

def mul_num(a):# define a function
Replace by
def mul_num(n1,n2,n3):

Answer 2

a=0
Add this to the first code

Answer 3

Pay attention to scope of variables. If you wish to use n1, n2, n3 from outside the function then they should be declared in the function as global.
The parameter a has no purpose as a function input. It gets overwritten inside the function, so it may as well be removed from the parameter list.
Here is one way to fix the first function:
def mul_num():# define a function
global n1, n2, n3
a = n1 * n2 * n3
Be sure to remove the argument also where the main program calls mul_num().