---
id: 5d792538be4fe331f1a6c008
title: Part 104
challengeType: 0
dashedName: part-104
---
# --description--
Unfortunately, impure functions are necessary - if you don't use them, the application won't perform any I/O so won't do anything.
But we have an impure function that could be pure - `evalFormula`. It calls `document.getElementById(c + n).value`, but this value can change, even if the arguments don't.
Change these calls to `""` - the function is now pure but doesn't work.
# --hints--
See description above for instructions.
```js
const nos = code.replace(/\s/g, '');
assert(nos.includes('elemValue=n=>c=>""') && nos.includes('match=>""'));
```
# --seed--
## --before-user-code--
```html
Spreadsheet
```
## --after-user-code--
```html
```
## --seed-contents--
```html
```
# --solutions--
```html
```