Lesson 18 · Profit and Loss

Profit and Loss

MathematicsSubject
14 minEstimated read
Everything is measured from the cost price

Profit and loss percentages are always taken on the COST price. That single convention decides every answer in this unit.

The three quantities

Name What it is Short form
Cost priceWhat the seller paid to get the itemCP
Selling priceWhat the buyer actually handed overSP
Profit or lossThe difference between themSP − CP

Profit percentage is profit over CP times 100. Loss percentage is loss over CP times 100.

Never divide by the selling price

Dividing by 600 gives 16.7%, which is not what anyone in business means. CP is what the seller put at risk, so it goes underneath.

Working forwards

A 20 per cent profit means selling at 120 per cent of cost, so 1.2 × 500 gives 600 in one step. For a loss, the multiplier is less than 1.

Working backwards to the cost price

At a 20% profit, SP 600 is 120% of the cost price. So 1% is 5, and CP was 500. Taking 20% off 600 gives the wrong answer.

Discount is a different thing

Discount comes off the MARKED price, not the cost price. A shop can offer a discount and still make a profit.

A profit percentage and a loss percentage do not cancel

Two shirts sold at 900 each, one at 20% profit and one at 20% loss, is not break even. The trader loses 75 rupees.

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