title: Reducing amount of code required for interest calculations
body: <p>I have two functions that calculate the balance after a year and the final balance after 'N' number of years (compound interest). Is there a more efficient way to do this/ way to do it with less code?</p>
  <pre><code>def balance_after_a_year(init_sum, interest_rate):
      return init_sum * (100 + interest_rate) / 100
  
  def final_balance(init_sum, interest_rate, years):
      final_sum = init_sum
      for i in range(years):
          round_num = round(balance_after_a_year(final_sum, interest_rate), 2)
      return round_num 
  </code></pre>