{"slug":"percentage","name":"Percentage Calculator","category":"fortune","tags":["everyday"],"tagline":"What is X% of Y, X is what percent of Y, and percent change — all three, correctly.","endpoint":"https://xearno.tools/api/v1/tools/percentage","page":"https://xearno.tools/t/percentage","description":"The three percentage questions people actually ask: a percent of a number, what percent one number is of another, and the percent change between two numbers — with the classic traps (reversal, asymmetric change) called out.","inputSchema":{"type":"object","properties":{"mode":{"description":"Question","type":"string","enum":["percent-of","what-percent","change"],"default":"percent-of"},"x":{"description":"X","type":"number","default":15},"y":{"description":"Y","type":"number","default":80}},"required":[],"additionalProperties":false},"methodology":["X% of Y = (X ÷ 100) × Y.  X as a percent of Y = (X ÷ Y) × 100.  Percent change = (new − old) ÷ |old| × 100.","Percent change uses the absolute value of the starting number so direction stays meaningful for negative baselines."],"usage":"POST https://xearno.tools/api/v1/tools/percentage with a JSON body matching inputSchema."}