# Number Numerology (数字数理)

> Reduces a phone, licence-plate or account number to a number 1–81 (last four digits mod 80, or the digit sum) and reports its rating and traditional gloss from the 81 数理 table of five-grid numerology, plus the five-element mapping of its digits under the 河图 and the common 数字五行 conventions, digit counts and the digital root.

- Calculator id: `number-numerology` · Category: I Ching & Five Elements (`yijing`) · Tool name: `evaluate_number_numerology`
- Canonical page: https://tttkmbb.com/yijing/number-numerology · This document: https://tttkmbb.com/yijing/number-numerology.md · JSON definition: https://tttkmbb.com/yijing/number-numerology.json

## Purpose

Reduces a phone, licence-plate or account number to a number 1–81 (last four digits mod 80, or the digit sum) and reports its rating and traditional gloss from the 81 数理 table of five-grid numerology, plus the five-element mapping of its digits under the 河图 and the common 数字五行 conventions, digit counts and the digital root.

**Use when:** You want the traditional 81-number (数理) rating and five-element breakdown of a phone number, plate number, account tail or other digit string.

**Do not use when:** You want the five grids of a personal name (use name-numerology) or an I Ching hexagram cast from numbers (use meihua-yishu); ratings are cultural, not statements about luck.

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `number` | string |  | required | 4–20 digits (spaces, hyphens and a leading + are ignored), e.g. a phone number, the digits of a plate, or an account tail. |
| `method` | enum: last_four_mod_80 \| digit_sum |  | optional, default "last_four_mod_80" | How the number is reduced to the 1–81 range of the table. |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `numerology_number` | integer |  | The reduced number 1–81 looked up in the table. |
| `rating` | string |  | 吉 (auspicious), 半吉 (mixed) or 凶 (inauspicious) per the 熊崎氏 81 数理 table. |
| `meaning_keyword` | string |  | Eight-character gloss of the number as reproduced in the popular table (cultural, several textual variants exist). |
| `reduction` | string |  | How the numerology number was obtained. |
| `digit_five_elements` | object |  | Elements of each digit and element counts under the 河图 convention (1/6 Water, 2/7 Fire, 3/8 Wood, 4/9 Metal, 5/0 Earth) and the common 数字五行 convention (1/2 Wood, 3/4 Fire, 5/6 Earth, 7/8 Metal, 9/0 Water). |
| `digit_counts` | object |  | How often each digit 0–9 occurs. |
| `digit_sum` | integer |  | Sum of all digits. |
| `digital_root` | integer |  | Digit sum reduced repeatedly to a single digit (0 only for an all-zero number). |
| `repeated_digits` | string |  | Digits that occur more than once, with their counts. |
| `disclaimer` | string |  | Cultural framing of the result. |

## Formula

`last_four_mod_80: N = (last four digits) mod 80, 0 → 80. digit_sum: N = (sum of digits) mod 81, 0 → 81. digital_root = 1 + (digit_sum − 1) mod 9 (0 when digit_sum = 0). Rating and gloss from the 81 数理 table (1–81).`

The 81 数理 ratings and glosses are the widely reproduced table of 熊崎健翁's five-grid school (五格剖象法), with the three-level rating 吉/半吉/凶; published versions differ for numbers 40, 43, 50, 61 and 73. Traditional reference calculation from the Chinese divination and numerology literature: it reports what the tradition assigns to the cast or number, not a prediction and not medical, legal or financial advice.

## Data Sources

- Wikipedia (zh) – 五格剖象法 (five grids and the 81 数理 table) — https://zh.wikipedia.org/wiki/五格剖象法 (reference, retrieved 2026-09-24)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/number-numerology?number=…`
- `POST https://tttkmbb.com/api/v1/calculate/number-numerology` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/number-numerology · OpenAPI operationId `evaluate_number_numerology` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "number-numerology", "inputs": {…}}`

## Example

- Phone 13800001234, last four mod 80: inputs `{"number":"13800001234","method":"last_four_mod_80"}` → `{"numerology_number":34,"rating":"凶 (inauspicious)","meaning_keyword":"破家之身 见识短小","digit_sum":22,"digital_root":4,"repeated_digits":"0 ×4, 1 ×2, 3 ×2","digit_counts":{"0":4,"1":2,"3":2,"8":1}}`
- 0000 (remainder 0 → 80): inputs `{"number":"0000","method":"last_four_mod_80"}` → `{"numerology_number":80,"rating":"凶 (inauspicious)","digit_sum":0,"digital_root":0,"repeated_digits":"0 ×4"}`

```
GET https://tttkmbb.com/api/v1/calculate/number-numerology?number=13800001234&method=last_four_mod_80
```

## Limitations

You want the five grids of a personal name (use name-numerology) or an I Ching hexagram cast from numbers (use meihua-yishu); ratings are cultural, not statements about luck. The 81 数理 ratings and glosses are the widely reproduced table of 熊崎健翁's five-grid school (五格剖象法), with the three-level rating 吉/半吉/凶; published versions differ for numbers 40, 43, 50, 61 and 73. Traditional reference calculation from the Chinese divination and numerology literature: it reports what the tradition assigns to the cast or number, not a prediction and not medical, legal or financial advice. All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**Why the last four digits?**

Popular phone-number numerology takes the last four digits (the personal part of a Chinese mobile number) mod 80 so the result falls in 1–80 of the 81 table; the digit-sum method uses the whole number.

**Which five-element mapping is right?**

Both are in use: the 河图 (River Map) pairs 1/6 Water, 2/7 Fire, 3/8 Wood, 4/9 Metal, 5/0 Earth; the popular 数字五行 uses 1/2 Wood, 3/4 Fire, 5/6 Earth, 7/8 Metal, 9/0 Water. The output shows both.

## Related

- [Name Numerology – Five Grids (五格剖象法)](https://tttkmbb.com/yijing/name-numerology.md) — Same 81 数理 table applied to the five grids of a name.
- [Five Elements Relation (五行生克)](https://tttkmbb.com/yijing/five-elements.md) — Generating and controlling relations of the digit elements.
- [Plum Blossom Numerology (梅花易数)](https://tttkmbb.com/yijing/meihua-yishu.md) — Cast an I Ching hexagram from numbers instead.