python 3.x – Game: Predict answer based on 3 user inputs, 2 self created inputs

add9 = ()

add9.append(int(input("Enter 1st 4-digit no.: ")))

print(f"The answer will be 2 and {str(add9(0))(0 :-1)} and {str(add9(0)-2)(-1)} = 2{add9(0)-2}")

add9.append(int(input("Enter 2nd 4-digit no.: ")))

add9.append(9999-add9(1)) 

print(f"The 3rd 4-digit is 9999 - {add9(1)}= {add9(2)}")

add9.append(int(input("Enter 4th 4-digit no.: ")))

add9.append(9999-add9(3)) 

print(f"The 5th 4-digit is 9999 - {add9(2)}= {add9(4)}")


print(f"""
So, 
{add9(0)}+{add9(1)} = {add9(0)+add9(1)}
{add9(0)+add9(1)}+{add9(2)} = {add9(0)+add9(1)+add9(2)}
{add9(0)+add9(1)+add9(2)}+{add9(3)} = {add9(0)+add9(1)+add9(2)+add9(3)}
{add9(0)+add9(1)+add9(2)+add9(3)}+{add9(4)} = {add9(0)+add9(1)+add9(2)+add9(3)+add9(4)}
""")

gives

Enter 1st 4-digit no.: 9999
The answer will be 2 and 999 and 7 = 29997
Enter 2nd 4-digit no.: 2345
The 3rd 4-digit is 9999 - 2345= 7654
Enter 4th 4-digit no.: 6789
The 5th 4-digit is 9999 - 7654= 3210

So,
9999+2345 = 12344
12344+7654 = 19998
19998+6789 = 26787
26787+3210 = 29997


(Program finished)

Code works fine.
It’s for kids to demo how to produce output using 3 inputs from user.
The trick is to subtract 9999 from 2nd and 3rd input from user.
I have tried to use as small syntax as possible.