# Wolfram Alpha + LaTeX revisited

I mentioned before how useful it can be to evaluate numerical LaTeX expressions with Wolfram Alpha using Alfred. I still do that a lot, but now that I have a Wolfram Alpha pro subscription, I'm spending more time on the WA website itself to take advantage of features like calculation history.

Another benefit of being on the website is being able to visually see how WA interprets the code I enter. This is a fantastic way to verify that I entered the code that I thought I enteredâ€”especially for longer expressions that go beyond the visible boundary of the input field.

A recent example: I wanted to evaluate:

`\frac{1677 - 1251.76}{1 + \frac{(1-0.004)}{1.04} + \frac{(1-0.004)(1-0.005)}{1.04^{2}} + \frac{(1-0.004)(1-0.005)(1-0.006)}{1.04^{3}} }`

The first time I copied this expression into WA, I accidentally missed the very last bracket, probably because there was some extra space in front of it.

```
<img src="/img/img.png" alt=""/>
```

I was able to quickly see that something was wrong since I intended the `1677 - 1251.76`

term to be in the numerator.

So I tried again, making sure to capture all of the code, and got what I was looking for, including the numerical value of the expression, 113.41.

```
<img src="/img/img.png" alt=""/>
```

Being able to evaluate these expressions on the fly is a godsend and greatly reduces the chances for typos in the final document. As an added bonus, since WA generates a unique URL for each query, I can copy it into my `.tex`

file as a comment for later reference. For example, here's the calculation above.