Simple Savings Calculator spreadsheet
This example shows how to build a spreadsheet to calculate savings interest, to accompany section 9.3 of the book. More detailed instructions can be found below.
Creted by the book authors - free for educational use.
Figure 9.3.2 – Simple Savings Calculator
Interest
Adam is 25. He is looking to save money for a pension starting with £100. He has been offered an investment paying 3% per year interest.
- If he leaves the interest to 'compound' in the investment, how much will it be worth at age 65? (£326)
- If he continues to add 100 each year (£2 a week) what will the total be? (around £8,000)
- How does this compare with the total he has invested? (£4,000, i.e. doubled)
See the tab 'Simple Savings Calculator' for a simple example of investigating this with a spreadsheet.
- Look at how this spreadsheet was made and try and create your own version.
- Try changing the interest rates and annual deposit amounts to see how much the account is worth after 25 years.
- Add another column to show the total amount that Adam has paid in (without interest) each year.
Note:
- When you format a cell as "percentage" the spreadsheet automatically shows 100x the actual value. Try changing the format of the interest rate cell to 'Number' and see what happens. That's why the calculations don't have a "/100" in them.
- Since so many countries call their currency 'dollars' and most people recongise the $ sign we have used that here – you can change this using the spreadsheet's formatting functions if you wish.
- To 'name' a cell, select the cell, go to the top left of the screen where the cell reference (e.g. 'C3') is displayed and change it to a name like 'interest' – you can then use the name 'interest' in calculations instead of '$C$3'.
