Ask HN: Where do you do quick back of envelope calculations? | Hacker News Reader

Ask HN: Where do you do quick back of envelope calculations?

7 pointsadamlangsner18 comments

Before Apple killed the Dashboard in Catalina. I had this widget called FormulaCalc that I loved.

It was very basic, screenshot below. It had two long text fields on top of each other. You'd enter a mathematical expression in JS in the top field (e.g. "3 + 4 / ( 5 * 0.9 + pi) + pow(2, 4)" ) and as you typed it would auto-generate the result in the bottom field in real time. I would have several instances of this widget in my dashboard so I could quickly and easily do simple calculations or do multipart calculations, copying the result from one widget into the input field of another.

I'd use it constantly for things like measuring stuff for frontend work, doing some rough analytics from db queries, or even just back of envelope budgeting / tax stuff. Using it was so automatic and immediate that it became such an essential tool.

Screenshot: http://www.mindlessflash.com/formula_calc.png

Since I upgraded my OS I've been using the evaluator in Spotlight and the calculator app on my phone and it's not as good because you can only work with one formula at a time. So I guess I have two questions:

1. How do you do rough calculations day to day, what tools do you use and are you happy with them?

2. Do you know of any products / solutions that are similar to the dashboard widget I described above?

On the back of an envelope?

Seriously: with a pen, a scrap of paper, and a calculator.

If I want to keep the calculation I'll copy it to a plain text document or to a spreadsheet, or copy it to a notebook.

Also, if you have a browser open, you can just type equations into the console (using JS syntax):

  > 3 + 4 / ( 5 * 0.9 + Math.PI) + Math.pow(2, 4)
  < 19.52345108949519

Edit: or just open Terminal, type 'python', and use in interactive mode:

  >>> import math
  >>> 3 + 4 / ( 5 * 0.9 + math.pi) + math.pow(2, 4)
  19.52345108949519

Do you find that this workflow disrupts your flow at all when you're working? Also, do you have any difficulty keep track of all the different calculations?

No it's fine. I almost always have a browser and a text editor open, so cut & paste between them is quick. console keeps all the calculations until cleared. If I have a geometry problem I always sketch a diagram with pen and paper first.

(btw the Mac Calculator.app has a 'paper tape' feature that also keeps a record of calculations. ⌘T)

Formula Calc sounds great, where can I download it? I'm enjoying life on legacy OS X versions over here! 8)

Edit: Answering my own question: https://www.apple.com/downloads/dashboard/calculate_convert/...

What do you currently do for quick calculations?

I uploaded a copy to my s3 bucket: https://www.mindlessflash.com/FormulaCalc.wdgt.zip remove the .zip extension before opening on it.

I should say the version I linked to, I hacked a bit to make the text fields wider to fit more text in them

I currently use Spotlight, but it's super non-ideal. I'll often dismiss spotlight and then realize I forgot the result. (I really hate what they did to Spotlight in Yosemite—it's overloaded and thus worse at its original purpose of searching the filesystem.)

I also recently bought Soulver (https://www.acqualia.com/soulver), which is great but not quite as quick as a dashboard widget.

Thanks for the modified upload—I realized the version on Apple's site has a visual glitch with the search bar length. I also found this version, which makes you hint enter before you can see the result, but feels more polished. Can't tell if there's any relation. https://www.apple.com/downloads/dashboard/calculate_convert/...

Thanks. I'll check out soulver, it seems a bit linear though. I don't know about you but I'm looking for something that's more like plugging inputs into outputs and wiring up calcs than doing them line by line.

Not exactly what you were asking for, but I really like Soulver [1]. It's a natural-language-ish calculator. The interface is similar to a REPL where you can name/recall and evaluate. The only downside is it's a bit pricey at $30.

[1] https://soulver.app

Thanks! Is there anything you dislike about soulver other than the price?

There's only one thing I'd mention which is that version 3 changed the document model.

In version 2 you could make independent files and put them anywhere. It seems, though I may be wrong as I haven't used v3 much, that they want you to keep all your files in one central location and not have independent Soulver files.

I use wolframalpha.com

Here is the result of the equation from the OP https://www.wolframalpha.com/input/?i=3+%2B+4+%2F+%28+5+*+0....

what if you need do multi-step calculations? do you find wolframalpha agile enough or is it cumbersome to use for quick things?

Excel. If there was a faster loading "tiny spreadsheet" that would just pop open, I would love it.

Thanks! What type of quick calculations do you typically do in excel?

I do many. Sometimes I am on a call and someone mentions numbers I have to track. Sometimes I have to do a series of discount rates over time. I look at a lot of ratios. Even when I do complicated calculations, I like to look at the intermediate steps over time.

Since I'm mostly in the terminal, I just pop up a Lua prompt and do the calculation there - any repl will do, honestly :)

Like a few others here, I typically use an interactive Python console.

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