FA-84354 / Betting odds conversion / Member archive

Favourite moneyline computed with the underdog formula · case 04

A 1.50 price is shown as -50 instead of -200.

Member previewVariant 4 · 3 implementations · 9 checks per implementation

Case contract

Convert a decimal price string to an American moneyline string. Prices at or below 1 return "invalid". For d >= 2 the line is "+" followed by 100 * (d - 1); for d < 2 it is "-" followed by 100 / (d - 1). The magnitude is computed exactly from the decimal text and rounded half up to an integer. Evens (2.00) is "+100".

Why this case matters

Sportsbooks display the same price in decimal and American formats and must agree at every boundary.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
control favourite	`"-50"`	`"-200"`	Failed

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