Profit & Loss — Shopkeeper's Maths
✨ IN SHORT — THE WHOLE LESSON IN 20 SECONDS
Profit % and Loss % are ALWAYS calculated on Cost Price (CP) — the price the seller paid. Remember 'CP is the boss' and this whole chapter obeys you.
1. The Core Formulas
Profit = SP − CP. Loss = CP − SP. Profit% = Profit/CP × 100. Loss% = Loss/CP × 100. SP when profit p%: CP × (100+p)/100. SP when loss l%: CP × (100−l)/100.
📌 CP ₹500, SP ₹575. Profit 75. Profit% = 75/500 × 100 = 15%.
2. Finding CP from SP
CP = SP × 100/(100+p) for profit; CP = SP × 100/(100−l) for loss. Sold at ₹880 with 10% loss → CP = 880 × 100/90 = ₹977.78 — always more than SP in a loss, sanity check!
💡 Trick: In profit, CP < SP. In loss, CP > SP. If your CP breaks this rule, you divided the wrong way.
3. Discount (Marked Price)
Discount is always on Marked Price (MP): SP = MP − Discount. Discount% = Discount/MP × 100. MP ₹1,000, 20% off → SP ₹800. Successive discounts multiply: 20% then 10% = pay 0.8 × 0.9 = 0.72 → 28% total off.
📌 Two discounts 50% + 50% is NOT free! Pay 0.5×0.5 = 25% of price.
⚡ Now Practise — 8 Questions
Tap an answer. Right or wrong, we explain why instantly. Learn from every tap!
Q1. CP = ₹400, SP = ₹460. Profit % is:
Q2. An article bought for ₹250 is sold at 20% loss. SP is:
Q3. Sold at ₹720 with 10% profit. CP is (approx):
Q4. MP = ₹1,500, discount 30%. SP is:
Q5. CP ₹800 sold at ₹800 after marking ₹1,000. Discount % given is:
Q6. Successive discounts of 20% and 20% equal single discount of:
Q7. A watch sold at ₹990 causes 10% loss. CP was:
Q8. If CP of 10 pens = SP of 8 pens, profit % is:
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