Question: This is a [cops-and-robbers](/questions/tagged/cops-and-robbers "show questions tagged 'cops-and-robbers'") puzzle, the cops' thread can be found [here.](https://codegolf.stackexchange.com/questions/107012/hidden-inversions-cops-thread)

Your task will be to find an anagram of the provided programs in the cops' thread that performs its left inverse.

Once you crack an answer post the solution as an answer below and notify the original answerer.

You will be scored on the number of programs you are the first to crack.

Answer: 
7, 9 bytes, [ais523](https://codegolf.stackexchange.com/a/107033/18535)
-----------------------------------------------------------------------

```
00000000: 0173 dc25 7e13 dcb6 1f                   .s.%~....

```

Because brute force always wins, and 9! is only 362880
JavaScript (ES6), 46 bytes, [SLuck49](https://codegolf.stackexchange.com/a/107255/42545)
========================================================================================

**Original (calculates ln(x+1))**

```
x=>Math.log(x+(+String(t=985921996597669)[5]))

```

**Crack**

```
x=>Math[(lg=19979699+55686).toString(9+25)](x)

```

I never would have cracked this if I hadn't realized that the inverse is a [`Math` built-in](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/expm1). `(lg=19979699+55686).toString(9+25)` is just a convoluted way of returning `"expm1"`.