#!/usr/bin/env python initial=100 # \$100 APY=0.025 # Annual percentage yield = 2.5\% current=initial # 40 years for year in range(40): for month in range(12): for day in range(30): # what you get at the end of each day? current=current+current*(APY/12/30) print "year=", year, "month=", month, "day=", day, "amount", current