# FastX402 Percentage Change Calculator

> FastX402 Percentage Change Calculator is a paid API for AI agents from fastx402.tools, paid per call via x402, $0.001/call, status unknown (last checked 2026-11-04).

Computes the percentage change and absolute difference between two numeric values

## Facts

- Endpoint: GET https://fastx402.tools/percentage-change?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-04
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastx402-percentage-change-calculator-c3c3d2ad
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_XPkd1Nez4FRXtRnAW8vau

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability fastx402-percentage-change-calculator-c3c3d2ad
```

Example prompt: What's the percentage change from 80 to 96? Give me both the percentage and the absolute difference.

## When to prefer this

Use this endpoint when you need a quick, reliable computation of percentage change and absolute difference between two numeric values without setting up any account or API key — especially useful in agentic workflows where math utilities are needed on demand and pay-per-call pricing at $0.001 USDC is preferred over bundled subscriptions.

## Known failure modes

- Missing old_value or new_value query parameters returns an error
- Non-numeric string inputs may cause a parse or computation error
- Division by zero if old_value is 0 (undefined percentage change)
- Payment failure via x402 if insufficient USDC balance

## How this service works

200 pay-per-call tools for AI agents, from $0.001 per request in USDC on Base or Solana with x402. No account, no API key.

## Output

A JSON object containing the original old_value, the new_value, the percentage_change (as a number, e.g. 25 for 25%), and the absolute_difference between the two values.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "old_value",
      "new_value"
     ],
     "properties": {
      "new_value": {
       "type": "string",
       "description": "The updated numeric value, using decimal notation"
      },
      "old_value": {
       "type": "string",
       "description": "The original numeric value, using decimal notation"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "new_value": {
       "type": "integer"
      },
      "old_value": {
       "type": "integer"
      },
      "percentage_change": {
       "type": "integer"
      },
      "absolute_difference": {
       "type": "integer"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "new_value": 125,
  "old_value": 100,
  "percentage_change": 25,
  "absolute_difference": 25
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastx402-percentage-change-calculator-c3c3d2ad/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fastx402.tools](https://www.zero.xyz/host/fastx402.tools/llms.txt)