ForHosting KIT · Developer Utilities

Factorion checker

A factorion is a positive integer that equals the sum of the factorials of its own decimal digits.

● BetaFree · in your browser

Use it from WebAPIEmailTelegramApp soon

Classic examples are one hundred forty-five, because one factorial plus four factorial plus five factorial is one plus twenty-four plus one hundred twenty, and forty thousand five hundred eighty-five, built the same way from its five digits. Students, contest solvers, and recreational number theorists often need a quick yes-or-no verdict with an auditable breakdown of each digit contribution. This factorion checker accepts a single positive integer, expands its digits, looks up each digit factorial, sums those values, and reports whether the sum matches the original number. Values below one are rejected as invalid input so the contract stays aligned with the usual positive-integer definition used in textbooks and coding challenges.

How to use it

Enter your values in the form above. The tool checks them before calculating and shows the result on the same page.

Check your inputs

Use the labels and units shown next to each field. If something is missing or outside the allowed range, the page points to the field to fix.

Use it again or automate it

Use the browser tool for individual checks and the API when you need the same capability in an automated workflow.

What you can do with it

Get an answer now

Enter one set of values and see the result without building a spreadsheet or script.

Compare scenarios

Change one value at a time and rerun the calculation to understand what affects the result.

Automate repeated work

Use the API when the same calculation needs to run inside your product or workflow.

FAQ

How do I use this capability?

Complete the fields above and run it on this page. The form highlights anything that needs attention.

For developers — API access

Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.

API endpoint

POSThttps://api.kit.forhosting.com/numth/factorion-check

Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.

Call it from your stack

curl -X POST https://api.kit.forhosting.com/numth/factorion-check \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"n":145}'

const res = await fetch("https://api.kit.forhosting.com/numth/factorion-check", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "n": 145
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/numth/factorion-check",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "n": 145
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/numth/factorion-check", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"n":145}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"n":145}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/numth/factorion-check", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "n": 145
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "numth.factorion_check",
  "status": "queued",
  "_links": {
    "result": "/tasks/tsk_…/result"
  }
}

The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.

Pricing

Per request$0.002

Published price — no tokens, no invented credits. A failed task is never charged.

Errors

HTTP	Code	Meaning
`401`	`unauthorized`	Missing or invalid API key.
`402`	`insufficient_balance`	Your balance doesn't cover the task price.
`404`	`unknown_type`	That task type doesn't exist.
`429`	`rate_limited`	Too many requests. Use the webhook instead of polling.

Read the full KIT documentation →