Simple Interest · Grades 8–11
Simple Interest Worksheets
Simple interest problems built from clean, whole-dollar principals and tidy rates, so every calculation lands on an exact answer. Beginner uses whole years, and the higher levels add rates like 2.5% and half-year terms, the first step toward real-world financial literacy.
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What it is
Simple interest is money earned (or owed) on a principal amount, calculated as a fixed percentage of that principal for every year it's invested or borrowed. Simple interest formula: I = P × r × t.
Why it matters
A student who can compute simple interest by hand can look at a real loan or savings offer and know whether the advertised number is actually good, long before they ever open a bank account.
How to do it
- Find the interest earned in one year: multiply the principal by the interest rate.
- Multiply that yearly amount by the number of years.
- That total is the simple interest, add it to the principal for the final balance, if asked.
Examples by level
Find the simple interest for each investment.
- Beginner$200 at 2% for 3 years =Answer$12
- Intermediate$300 at 2% for 2 years =Answer$12
- Advanced$3100 at 2.5% for 5 years =Answer$387.50
Examples are generated by the same engine as the worksheets, so they're always mathematically correct. Built to avoid repeats, not reshuffle the same handful of questions.
Common mistakes
- Forgetting to convert the percentage rate by dividing by 100 before multiplying.
- Multiplying by the number of years twice (once implicitly, once explicitly).
- Confusing the interest amount with the final total balance.
Tips
- 'Simple' interest is always calculated on the ORIGINAL principal, not on a growing balance, that's compound interest, a different formula.
- The final balance (if asked) is the principal plus the interest, not just the interest alone.
For parents
Connect this to a real savings account or loan statement if you have one handy, seeing real numbers makes the formula concrete.
For teachers
Keep principals as clean multiples of $100 while the formula itself is new; introduce messier numbers only once the three-step process (rate → per-year → total) is automatic.
Key vocabulary
- principal
- the original amount of money invested or borrowed
- interest rate
- the percentage of the principal charged or earned per year
Frequently asked questions
- What grade is simple interest taught in?
- Simple interest is introduced in Grade 8 as part of the financial literacy strand, building on the percentage skills learned in Grades 6-7, then continues through Grades 9-11.
- What's the difference between simple and compound interest?
- Simple interest is always calculated on the original principal. Compound interest is calculated on the growing balance (principal plus previously earned interest), so it grows faster over time.
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