How to assign operator's parameters to user input and assign operator to var outside of if statement and calling var inside of if?

I just started learning Python a few days ago and I absolutely love it! OK so I had already built a very rudimentary calculator but I wanted to make it more advanced and simplify it. I know its just a calculator now but I wanted to write and structure it as if it were in a much larger program or algorithm. I'm not done with the last portion of the if statement I know that but I wanted to figure out how I could assign user input to an operators parameters and assign that operator to a variable outside of an if statement, and then assign user input a value and call on that variable inside of the if statement?

import math
import operator

user_num_00 = 0.0
user_num_01 = 0.0
num_ui_list = [" first ", " second ", " base ", " power ", ""]
operator_list = {
    "1": operator.mul,
    "2": operator.truediv,
    "3": operator.add,
    "4": operator.sub,
    "5": operator.pow,
    "6": math.sqrt
}
operation_ui_list = {
    "1": " * ",
    "2": " / ",
    "3": " + ",
    "4": " - ",
    "5": " to the power of ",
    "6": " to the root of "
}


def num_ui(x=num_ui_list[0]):
    return "Enter the" + x + "number: "


def num_ui_answer(num_0, y, num_1, z):
    num_answer = num_0 + y + num_1 + " = " + z
    return num_answer


user_input = input("1. Multiplication\n2. Division\n3. Addition\n4. 
Subtraction\n5. Exponent\n6. Root"
                   "\nChoose an operation: ")
user_operation = operator_list[user_input]
user_operation_answer = user_operation(user_num_00, user_num_01)
operator_string = operation_ui_list[user_input]
if user_input == "1" or user_input == "2" or user_input == "3" or 
user_input == "4":
    user_num_00 += float(int(input(num_ui())))
    user_num_01 += float(int(input(num_ui(num_ui_list[1]))))
    print(num_ui_answer(str(user_num_00), operator_string, 
str(user_num_01), str(user_operation_answer)))

elif user_input == "5":
    user_num_00 = float(int(input(num_ui(num_ui_list[2]))))
    user_num_01 = float(int(input(num_ui(num_ui_list[3]))))

elif user_input == "6":
    user_num_00 = float(int(input(num_ui(num_ui_list[4]))))
    user_num_01 = ""

else:
    print("Error")