The tools in a financial plan
Compound Interest
Lump sum grows over time. FV = PV(1+r)ⁿ
Regular Savings
Equal contributions at regular intervals, annuity formula
Loans
Reducing balance, repayments over time, total interest
Financial planning questions combine these tools. A typical exam question might ask: "Sarah wants to save $30,000 for a house deposit in 5 years. She invests a lump sum and makes regular contributions. What total does she accumulate?"
The key is identifying which tool applies to which part, lump sum → compound interest, regular deposits → annuity formula.
Future value of regular contributions
When you deposit the same amount at the end of each period, the total you accumulate is the sum of each deposit grown with compound interest. The formula adds all those future values at once.
PMT = regular payment · r = interest rate per period · n = number of periods
How to verify with clean numbers: multiply the result you expect by r, add 1, subtract (1+r)ⁿ, and check it equals zero, or just verify by adding up the individual contributions grown with compound interest.
$100 is deposited at the end of each year for 2 years into an account earning 10% p.a. Find the total accumulated.
Verify by tracking each deposit:
| Deposit | When deposited | Grows for | Value at end |
|---|---|---|---|
| $100 | End of year 1 | 1 year | $100 × 1.10 = $110 |
| $100 | End of year 2 | 0 years | $100 × 1.00 = $100 |
| Total | $210 ✓ | ||
$200 deposited annually for 3 years at 10% p.a. Find the accumulated amount.
Verify:
Planning to reach a savings goal
If you know the target FV and want to find the required annual deposit PMT, rearrange the formula:
You want to save $2,200 over 2 years by depositing equal amounts annually at 20% p.a. How much must you deposit each year?
Superannuation, the big financial plan
Superannuation is a long-term retirement savings plan. Employers contribute a percentage of your salary (currently 11%), and you can add voluntary contributions. It works like a regular savings annuity over 40+ years, with compound growth.
- Regular contributions (employer + voluntary)
- Compound growth over decades
- Small early contributions = big results
Super questions use the FV annuity formula. Identify the annual contribution (PMT), annual rate (r), and years to retirement (n). Then apply FV = PMT × [(1+r)ⁿ − 1] / r.
Practice Questions
Verify:
Deposit 1: $1,000 × 1.20¹ = $1,200
Deposit 2: $1,000 × 1.20⁰ = $1,000
Total = $1,200 + $1,000 = $2,200 ✓
Try n = 1: 1,000 × 1.30 = 1,300 ✗
Try n = 2: 1,000 × 1.69 = 1,690 ✗
Try n = 3: 1,000 × 2.197 = 2,197 ✓ → 3 years
🌏 Ready to test yourself?
Life Plan escape room, 6 financial planning challenges to unlock your future.