Pricing/Discount & Markdown Calculator mechanism

Model scope

The sequential-stacking rule is mathematically sound under percentage-point inputs, but the instrument is incomplete and cannot honestly claim to compute the required discount to hit a target without a target-price input and explicit formula. The label 'Educational estimate' is appropriate, provided the calculator does not present tax, fee, or individualized financial advice.

• The sale-price formula is correct only when discount is represented as a decimal fraction; if the input is a percentage value such as 20, the formula must be sale = list * (1 - discount_percent / 100).
• Sequential stacked discounts correctly multiply remaining-price factors: final = list * product(1 - discount_i / 100).
• The required-discount-to-target calculation is claimed but no formula or target-price input is specified. For one overall discount, it should be required_discount_percent = (1 - target_price / list_price) * 100.
• The formulas for total dollar off and effective discount percentage are missing. They should be total_dollar_off = list_price - final_price and effective_discount_percent = (1 - final_price / list_price) * 100.

Units and conventions

• Prices are expressed in the same currency and numeric unit, with no tax, shipping, fees, or currency conversion included.
• Discount inputs are percentage points, so 20 means 20%, not 0.20.
• For stacked discounts, each discount is applied sequentially to the price remaining after the prior discount.
• Required discount to target is interpreted as one equivalent overall discount unless a separate stacking schedule is explicitly provided.
• Currency rounding is not specified; calculations below use exact arithmetic before any display rounding.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "list_price": 100,
    "discount_percent": 20,
    "stacking": false,
    "target_price": 80
  },
  "expected_outputs": {
    "final_price": 80,
    "total_dollar_off": 20,
    "effective_discount_percent": 20,
    "required_discount_percent": 20
  },
  "working": "Sale price = 100 * (1 - 20/100) = 100 * 0.80 = 80. Total $ off = 100 - 80 = 20. Effective discount = (20/100) * 100% = 20%. Required discount to reach 80 = (1 - 80/100) * 100% = 20%."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

A zero list price produces undefined required discount and undefined effective discount because the formulas divide by list price. The instrument should reject the input or display an explicit undefined result.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json