#
# interest.py
# worked in class on Sep 13
#
#  $100, at 5% per year, for 10 years,
#  compounded monthly

principle = 100   # in dollars
interest =  0.05  # per year
interest_per_month = interest / 12
years = 10

for month in range(12 * years):
    principle = principle + (principle * interest_per_month)
    # principle = principle * (1 + interest_per_month)
print "The answer is", principle