I made this basic python calculator - it just does addition, subtraction, division, and multlipication. I feel like the code is a mess, but it does what I want it to, and I feel like it does it effectively.

import operator

def calculate (first_number, operation_type, second_number):
    if operation_type == 'a':
        answer = first_number + second_number
        answer_text = f"{first_number} + {second_number} = {answer}"
    if operation_type == 's':
        answer = first_number - second_number
        answer_text = f"{first_number} - {second_number} = {answer}"
    if operation_type == 'm':
        answer = first_number * second_number
        answer_text = f"{first_number} x {second_number} = {answer}"
    if operation_type == 'd':
        answer = first_number / second_number
        answer_text = f"{first_number} \xF7 {second_number} = {answer}"
        
    return answer_text

while True:
    while True:
        try:
            first_number = int(input("Enter first number: "))
            break
        except ValueError:
            print ("Enter a number!\n")
            pass

    while True:
        operation_type = str(input("\nA - add\nS - subtract\nM - multiply\nD - divide\nEnter operation type: "))
        operation_type = operation_type.lower()
        
        if operation_type in {'a', 'm', 'd', 's'}:
            break
        else:
            print ("Invalid operation type!\n")
            pass

    while True:
        try:
            second_number = int(input("\nEnter second number: "))
            break
        except ValueError:
            print ("Enter a number!\n")
            pass

    print (calculate (first_number, operation_type, second_number))
    
    run_again = str(input("Run again? Type 'y' to continue, or q to quit: "))
    if run_again.lower() == 'y':
        pass
    if run_again.lower() == 'q':
        break
    elif run_again.lower() != 'y' and run_again.lower() != 'q':
        print ("Invalid entry")
        break