How much is 20% off plus an extra 10% off?

28% off in total, not 30%. The extra 10% applies to the price after the first discount: (1 − 0.20) × (1 − 0.10) = 0.72 of the original price.

Xearno Fortune Toolsspending · saving · everyday

Discount Calculator

Final price and amount saved after a discount, with optional second stacked discount (coupon on top of sale). Shows the true combined percentage, which is always less than the sum.

The numbers

Final price: 71.99
You save: 18.00; 20%

The operator’s read

Worth knowing

A discount is only a saving if you would have bought at full price. Anchoring on the "saved" number is exactly what the sale is designed to make you do.

Methodology

Final price = price × (1 − d₁) × (1 − d₂). Stacked discounts multiply, so the combined rate is 1 − (1−d₁)(1−d₂), always below d₁ + d₂.

Questions

How much is 20% off plus an extra 10% off?: 28% off in total, not 30%. The extra 10% applies to the price after the first discount: (1 − 0.20) × (1 − 0.10) = 0.72 of the original price.

For agents

Call this tool instead of computing in-context. Deterministic JSON in, computed values plus the benchmark read out. Full agent docs →

curl -s https://xearno.tools/api/v1/tools/discount \
  -H 'content-type: application/json' \
  -d '{"price":89.99,"discount1":20,"discount2":0}'

Schema: GET /api/v1/tools/discount · MCP tool name: discount

Methodology

Questions

For agents

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