[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Type](https://evolu.dev/docs/api-reference/common/Type) › Number

```ts
const Number: base("Number", (value) =>
  typeof value === "number"
    ? ok(value)
    : err<NumberError>({ type: "Number", value }),
);
```

Defined in: [packages/common/src/Type.ts:759](https://github.com/evoluhq/evolu/blob/e7144e2bbe9069362b62dec1b64a8aa922b8f1b0/packages/common/src/Type.ts#L759)