Discount Basics

🎯 Learning Objective

Calculate discount, discount% and selling price from the marked price using multiplying factors.

💡 Concept

• Discount is ALWAYS calculated on MP (marked price), never on CP
• Discount = MP − SP
• Discount% = (Discount/MP) × 100
• SP = MP × (100 − d)/100 — the MF for 15% off is 0.85
• No discount mentioned → SP = MP

🧮 Key Formulas

Discount = MP − SP

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Discount% = (Discount × 100)/MP

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SP = MP × (100 − d)/100

✏️ Easy Example

Q. A shirt marked at ₹600 is sold at a 15% discount. Find the selling price.

1. Discount = 15% of 600 = ₹90
2. SP = 600 − 90

Answer: ₹510

🇮🇳 Real-Life Example

Diwali sale: jeans with MRP ₹1,200 carry a '25% OFF' tag — you pay 1200 × 0.75 = ₹900 at the counter. That mental maths is this lesson.

📝 Exam-Level Example

Q. A fan with a marked price of ₹1,500 is sold for ₹1,275. Find the discount per cent.

1. Discount = 1500 − 1275 = ₹225
2. Discount% = (225/1500) × 100

Answer: 15%

📝 Exam-Level Example

Q. After a 12% discount, a saree sells for ₹880. Find its marked price.

1. SP = MP × 0.88
2. MP = 880 ÷ 0.88

Answer: ₹1,000

🪄 Memory Trick

Discount lives on MP, profit lives on CP — two different homes. Never move one into the other's house.

⚠️ Common Mistakes

• ❌ Calculating discount% on CP or SP instead of MP
• ❌ Finding MP from SP by adding 12% back (divide by 0.88 instead)

🏆 Exam Tips

• ✅ MF for d% off = (100 − d)/100 — memorise 0.9, 0.85, 0.75 for 10%, 15%, 25%
• ✅ MRP printed on any packet is nothing but the MP of exam questions

📌 Summary

• Discount = MP − SP, always on MP
• Discount% = discount/MP × 100
• SP = MP × (100 − d)/100
• Reverse direction → divide by the MF