[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Types](https://evolu.dev/docs/api-reference/common/Types) › Digit1To51

```ts
type Digit1To51 =
  | Digit1To9
  | `${"1" | "2" | "3" | "4"}${Digit}`
  | `5${"0" | "1"}`;
```

Defined in: [packages/common/src/Types.ts:277](https://github.com/evoluhq/evolu/blob/e7144e2bbe9069362b62dec1b64a8aa922b8f1b0/packages/common/src/Types.ts#L277)

Numeric string 1-51. Useful for weeks validation.