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Margin is profit as a share of the selling price; markup is profit as a share of cost. Both matter when you set prices.
Cost ₹250, selling ₹320: profit ₹70. Margin = 70 ÷ 320 = 21.9%. Markup = 70 ÷ 250 = 28%. Quoting one when you mean the other is the most common pricing mistake.
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