Программа не выполняет 4-й пункт моего меню, который является валютным переводчиком

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def addition():                             #Addition

   a1 = int(input("Enter your first number: "))
   b1 = int(input("Enter secondary number: "))
   c1 = a1 + b1
   print("-------------------------------")
   print(a1," + ",b1," = ",c1," . ")
   print("-------------------------------")

def subtraction():                          #Subtraction

    a2 = int(input("Enter your first number: "))
    b2 = int(input("Enter your first number: "))
    c2 = a2-b2
    print("-------------------------------") 
    print(a2," - ",b2," = ",c2," . ")
    print("-------------------------------")

def multiplication():                       #Multiplication
    a3 = int(input("Enter your first number: "))
    b3 = int(input("Enter your first number: "))
    c3 = a3*b3

   
    print(a3," * ",b3," = ",c3," . ")
    

def division():                               #Division
    a4 = int(input("Enter your first number: "))
    b4 = int(input("Enter your first number: "))
    c4 = a4/b4
   
   
    
    print(a4," / ",b4," = ",c4," . ")
    
def mathmenu():
    print("1. Addition")
    print("2. Subtraction")
    print("3. Multiplication")
    print("4. Division")
    
def menu():
   

    print("")
    
    print("||||| 1. Math Operations                                      |||||")
    print("||||| 2. Personal Database                                  |||||")
    print("||||| 3. Message Encrypter/Decrypter                  |||||")
    print("||||| 4. Currency Translator                                 |||||")
    print("||||| 5. Open File                                               |||||")
    print("||||| 6. Dictionary                                               |||||")
    print("|||||               ")                                                   
    print ("             Welcome to Gage's Vault")
    
loop = True
while loop:
    menu()
    choice = int(input("What would you like to do today?: "))
    print("")
    print("")
    print("")
    
    if   choice==1:
        print("Math Operations")
        mathmenu()
        choice1 = int(input("Choose Math Operation: "))
    if choice1==1:
         addition()
    elif choice1==2:
         subtraction()
    elif choice1==3:
         multiplication()
    elif choice1==4:
          division()
                      
    elif choice==2:
       print("Personal Database")
       
    elif choice==3:
        print("Message Encrypter/Decrypter")
        
    elif choice==4:
        # All currency base integers are equilvalent to USD .01 penny
        # Resource = http://www.xe.com/currencyconverter/convert/?Amount=.01&From=USD&To=INR
        # Updated as of 28FEB18
        print("Currency Translator")
        print("-----------------------------------------")
        print("1. USD") #.01           /United States Currency
        print("2. Euro")#.00818015    /European Currency
        print("3. GPD") #.00719363     /British Pound
        print("4. INR") #.651016     /Indian Rupee
        
    elif choice==5:
        print("Open file")
        
    elif choice ==6:
        print("Dictionary")
        
    else:
        raw_input("Incorrect Calculation. Enter any key to continue......") 

Что я уже пробовал:

Я пытался в течение 3 часов, но ничего не добился с этой проблемой.

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