Python Print Displays -

i having problem project i'm working. problem having @ end of display list getting negative number, wondering if give me direction on how fix problem? need zero.

initalprice = float(input("enter price of computer: ")) month = 0 downpayment = initalprice * .10 balance = (initalprice - downpayment) aninterest = balance * .01 / 12 monthlypayment = balance * 0.05   print("%0s%20s%20s%20s%13s%23s" %("month", "current balance", "interest  owed", "principal owed", "payment", "balance remaining"))   in range(1, 100):      #aninterest = aninterest     if balance >= 0:         initalprice = initalprice - initalprice * .10           principal = monthlypayment - aninterest         balance = balance + aninterest - monthlypayment         print("%0d%20.2f%20.3f%20.2f%13.2f%23.2f" %(i, initalprice, aninterest, principal, monthlypayment, balance)) 

you subtracting constant amount monthlypayment (ie. 10% of balance). if balance plus interest less monthlypayment balance becomes negative. have simple check see not case.

p.s. recommend using while loop problem loop can either iterate many times, or not enough times.