## 4.2 Modelling Compound Interest Systems with Regular Withdrawals using Tables

Note: if you cannot remember how to model reducing balance systems with regular repayments, revise notes for 4.1 Modelling Compound Interest Systems with Regular Withdrawals.

### Guidelines to using a Table for Compound Interest Systems with Regular Withdrawals

**Tables**provide a convenient method for analysing compound interest systems with regular withdrawals, especially when there are regular systemic changes (e.g. the interest rate or withdrawals change regularly).- The columns of the table should list, the
**compounding period**,**withdrawal**,**interest earned**,**principal addition**(i.e. the amount the system has increased/decreased during each compounding period) and the**balance**at the end of the compounding period. - The
**principal addition**can be calculated as follows: