Simple & Compound Interest — Advanced explained through a friendly whiteboard conversation, examples, visuals, and practice for school students.
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Notes
Step 2
Formulae
Step 3
Examples
Step 4
Practice
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Interest is extra money paid or earned when money is borrowed or saved.
Simple interest is calculated on the original principal. Compound interest grows by adding interest to the amount.
This topic is used in savings, loans, investments, instalments, and growth problems.
Principal is the original money. Rate is the interest percentage for one year. Time is usually measured in years.
Simple interest uses the same principal every year.
Amount means principal plus interest.
Compound interest is different because interest is added to the principal after each period.
For the same principal, rate, and time greater than one year, compound interest is usually more than simple interest.
Definition: Principal is the starting money, rate is the yearly percentage, and time is the duration.
For Rs 5000 at 8% per year for 2 years, principa, rat, tim.
Meaning: Simple interest is calculated on the original principal.
Definition: Simple interesrincipal x rate x tim.
For Rs 1000 at 10% for 2 years, S x 10 x s 200.
Meaning: Amount is total money after adding interest.
Definition: Amounrincipanterest.
If principal is Rs 1000 and interest is Rs 200, amount is Rs 1200.
Meaning: Compound interest adds interest to the amount after each period.
Definition: For annual compounding, amoun.
The first year interest is added before the next year interest is calculated.
Meaning: The two methods grow money differently.
Definition: Simple interest uses fixed principal. Compound interest uses updated amount.
Compound interest can grow faster because interest earns interest.
Easy
Question: Find simple interest on Rs 2000 at 5% per year for 3 years.
Medium
Question: Find the amount for Rs 4000 at simple interest of 6% for 2 years.
Exam-level
Question: Find compound interest on Rs 10000 at 10% per year for 2 years, compounded annually.
Confusing interest and amount
Why it happens: Both are money answers.
Correct approach: Interest is extra money. Amount is principal plus interest.
Using simple interest formula for compound interest
Why it happens: The formulas both use P, R, and T.
Correct approach: Read whether the question says simple or compound.
Leaving months as years
Why it happens: Time units are copied directly.
Correct approach: Convert months to years when using a yearly rate.
What is principal?
Principal is the starting amount of money.
Why is compound interest more?
Because interest is added to the amount and can earn more interest.
What is amount?
Amount is the total money after adding interest.
Practise the same concept from this article. Your student profile may guide entitlement and follop recommendations, but it does not replace this concept.