Topic
Simple Interest
💰 Simple Interest – Basics
Discrete interest is on an investment amount (Principal) for a specified period A simple method of interest calculated at a fixed rate of interest.
📌 Definition
Interest calculated on principal onlyseparate interestcalled
🧮 Formula
SI = (P × R × T) / 100
- ✔ P = Principal
- ✔ R = Rate of Interest
- ✔ T = Time (in years)
💡 Amount
Amount (A) = P + SI
📊 Example
- ✔ P = ₹1000
- ✔ R = 10%
- ✔ T = 2 years
SI = (1000 × 10 × 2) / 100 = ₹200
Amount = 1000 + 200 = ₹1200
📏 Important notes
- ✔ Interest is calculated on principal amount only
- ✔ Interest does not change every year
- ✔ Easy calculation
Important Notes (TNPSC / Maths):
- ✔ SI Formula = (P × R × T) / 100
- ✔ Amount = P + SI
- ✔ Time always in years
Exams include “What is Simple Interest?”, “What is Formula?”, “How to calculate Amount?” Such questions are frequently asked.
🧮 Simple Interest Formulas
Key Formulas Used in Calculation of Separate Interest Exams are very important. These are basic methods to help you remember easily.
📌 Key formula
SI = (P × R × T) / 100
- ✔ SI = Simple Interest
- ✔ P = Principal
- ✔ R = Rate of Interest
- ✔ T = Time (in years)
💰 Total Amount
A = P + SI
🔄 Alternative formulas
1️⃣ Finding Principal (P).
P = (SI × 100) / (R × T)
2️⃣ Finding Rate (R).
R = (SI × 100) / (P × T)
3️⃣ Finding Time (T).
T = (SI × 100) / (P × R)
📊 Short Tricks
- ✔ 1 year interest = (P × R) / 100
- ✔ 2 years interest = 2 × (1 year interest)
- ✔ SI ∝ Time (Increasing Time increases SI)
📘 Example
- ✔ P = ₹2000, R = 5%, T = 3 years
SI = (2000 × 5 × 3) / 100 = ₹300
A = 2000 + 300 = ₹2300
Important Notes (TNPSC / Maths):
- ✔ SI = (P × R × T) / 100
- ✔ A = P + SI
- ✔ P, R, T formulas are important
Exams “Find P, R, T by Formula” Such questions are frequently asked.
🧮 Simple Interest – 10 examples
📘 Example 1
P = 1000, R = 10%, T = 2
SI = (1000×10×2)/100 = ₹200
📘 Example 2
P = 2000, R = 5%, T = 3
SI = ₹300
📘 Example 3
P = 1500, R = 8%, T = 2
SI = ₹240
📘 Example 4
P = 5000, R = 6%, T = 1
SI = ₹300
📘 Example 5
P = 2500, R = 4%, T = 5
SI = ₹500
📘 Example 6
P = 3000, R = 7%, T = 2
SI = ₹420
📘 Example 7
P = 1200, R = 9%, T = 3
SI = ₹324
📘 Example 8
P = 4000, R = 5%, T = 4
SI = ₹800
📘 Example 9
P = 3500, R = 6%, T = 2
SI = ₹420
📘 Example 10
P = 10000, R = 3%, T = 1
SI = ₹300
Quick Revision:
- ✔ SI = (P × R × T) / 100
- ✔ Amount = P + SI
People Also Ask
Quick answers for common questions
Interest calculated on capital only.
SI=P×R×T / 100
Initial amount on which interest is calculated.
Percentage of interest earned per annum.
The duration for which the money is invested.
Capital + Interest
Amount = P + SI
Amount = P + SI
SI = (1000 × 10 × 2) / 100 = ₹200
SI = (2000 × 5 × 3) / 100 = ₹300
R = (SI × 100) / (P × T) = 10%
Simple Interest → Principal only
Compound Interest → Principal + Interest
Compound Interest → Principal + Interest
