Calculating and printing a credit card balance
A good thing you can do is to create more functions, which return values in the dictionary form.

Pseudo-code:

def calculateCreditCardBalance(balance, annual_interest_rate, monthly_payment_rate):
    total_paid = 0
    curr_values = ["balance" =&gt; balance, "annual_interest_rate" =&gt; annual_interest_rate, "monthly_payment_rate" =&gt; monthly_payment_rate]
    foreach this_month in rage(1,13):
        month_values = calculate_month_values(curr_values)
        print_values(month_values)
        update_month_values(month_values,curr_values)
    print 'Total paid: ' + str(curr_values["total_paid"])
    print 'Remaining balance: '+ str(curr_values["total_paid"])