# Integer GCD

`integer-gcd` · version 1.0.0 · Numbers & math · free, no key needed

Compute the non-negative greatest common divisor of two canonical integer strings.

**Use when you need to: integer gcd · greatest common divisor of two integers · gcd of integers.**

## Supported

- integer gcd
- greatest common divisor of two integers
- gcd of integers

## Not supported

- least common multiple
- gcd of more than two integers
- floating-point gcd
- polynomial gcd

## Behavior

- Inputs are canonical integer strings: 0 or an optional ASCII minus followed by a non-zero leading digit.
- The input -0 is accepted and canonicalized to 0 before evaluation.
- Integers are parsed with BigInt. A plus sign, spaces, underscores, hex, scientific notation, empty strings, and leading zeros other than 0 are rejected.
- Each input may have at most 1000 digits excluding the sign.
- The result is the non-negative greatest common divisor as a canonical integer string.
- gcd(0, n) and gcd(n, 0) equal |n|. gcd(0, 0) is rejected as undefined.

## Input

- `a` (string, required): min length 1; max length 1001
- `b` (string, required): min length 1; max length 1001

## Output

- `value` (string, required): min length 1; max length 1000

## Limits

- max digits: 1000

## Example

Request input:

```json
{
  "a": "48",
  "b": "18"
}
```

Response:

```json
{
  "result": {
    "value": "6"
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "integer-gcd",
  "version": "1.0.0",
  "input": {
    "a": "48",
    "b": "18"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/integer-gcd/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"a":"48","b":"18"}'
```

The machine-readable contract is at [/v1/tools/integer-gcd/versions/1.0.0](/v1/tools/integer-gcd/versions/1.0.0).

### CLI

```sh
node cli.mjs run integer-gcd 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

## Related tools

- [Array integer GCD](/tools/array-integer-gcd): Compute the non-negative greatest common divisor of an array of canonical integer strings.
- [Integer LCM](/tools/integer-lcm): Compute the non-negative least common multiple of two canonical integer strings.
- [Array integer LCM](/tools/array-integer-lcm): Compute the non-negative least common multiple of an array of canonical integer strings.
- [Array integer min max](/tools/array-integer-min-max): Return the numeric minimum and maximum of canonical integer strings.
- [Array integer mode](/tools/array-integer-mode): Return the most frequent canonical integers, listing every mode in first-seen order.
- [Array integer ranks](/tools/array-integer-ranks): Assign competition (1224) ranks to canonical integers; ties share the minimum rank.