Young Geniuses · Ages 13 to 14
Compound Interest Word Problems
Apply the compound interest formula in real-world contexts. A Grade 8–9 financial maths worksheet with answer keys.
The learning journey
Every activity is one step. Here is where this one fits.
- PlayLearn the idea in a game
- Practise(you are here)Lock it in on paper
- ReviewCome back and keep it sharp
- MasterTake on a harder challenge
- AchieveEarn a certificate
About Compound Interest Word Problems
Compound Interest Word Problems asks upper-secondary learners to apply the compound interest formula to realistic money situations: an amount invested at a percentage rate, growing over a number of years. Each problem gives a starting principal, a rate, and a number of years, and the student calculates the final value, applying the idea that interest is earned on interest. Compound interest is one of the most useful pieces of financial mathematics a student learns, and it is a core Grade 8 to 9 expectation across the US, UK, Canada and Australia, with direct relevance to savings, loans and investments in real life. The word-problem format is the right vehicle because it forces students to identify the principal, rate and time period from a context and then apply the formula correctly, rather than just plugging numbers into an equation. The contexts are kept relatable and the figures chosen so the arithmetic stays manageable. Generous working space supports structured solutions, and answers are given to two decimal places as money. The five levels grow the principals, rates and time periods. Each page prints cleanly on a standard A4 sheet, and every level downloads with its own complete answer key. There is no advertising and no sign-up.
Common questions
- What formula is used?
- The compound interest formula, A = P(1 + r/100)ⁿ.
- What grade is this for?
- Grade 8 to Grade 9 learners aged 13 to 14.
- Is an answer key included?
- Yes, every level has its own complete answer key.
A hand for grown-ups
- Before you start
- A handful of real coins is the best possible resource here. Sort them together before you start.
- While they work
- Let them make the same amount in different ways — 20p as two 10s, or 10 + 5 + 5. Flexibility is the goal.
- Afterwards
- Give them a small real purchase to work out — "this is 30p, what change from 50?". Real stakes focus the mind.
- Watch out for
- Assuming a bigger coin is worth more (that a big 10p beats a small 20p). Handling real coins and their values fixes this.
- Away from the screen
- Play shop with real coins. Let them handle small real transactions and work out the change.
Where to go next
Chosen by the skills this activity practises.