# TS17007: A type assertion expression is not allowed in the left-hand side of an exponentiation expression. Consider enclosing the expression in parentheses.

> A type assertion `<T>x` is on the left of `**`. Add parentheses around it.

## What it means

An angle-bracket type assertion (`<number>x`) directly on the left-hand side of `**` isn't
allowed, for the same reason as unary operators ([TS17006](https://ts-r.dev/errors/TS17006/)). ts-r's parser reports
it.

## Example

```ts
declare const x: unknown;
export const y = <number>x ** 2;
```

## How to fix

- Wrap the assertion in parentheses: `(<number>x) ** 2`, or use `as`: `(x as number) ** 2`.

Source: https://ts-r.dev/errors/TS17007/