If you’re not comfortable with math then most scientific calculators will seem a little intimidating, packed as they are with complex functions which you’ll rarely, if ever use.

But it doesn’t have to be that way. OpalCalc is a very powerful calculator with some near spreadsheet-like functionality, yet it’s also presented in a way that makes it very accessible to even the most math-phobic of potential users.

The program opens with a simple, plain text interface, for instance. Type an equation in the left hand pane – 2 + 50 * 12 / 8, say – and the answer appears on the right: easy. The multiline interface also means it’s straightforward to edit and reuse some previous equation, which alone could justify your using the program over a conventional desktop calendar.

You don’t have to worry particularly about how you enter a calculation, either, as OpalCalc will do its best to figure out what you mean. Consider these lines, for example.

$80 + $400 for food and hotel
$350 for travel costs
$100 + 15% tax for room hire
$75 as £
total

It’s all very natural to read and write, yet OpenCalc has no problem with this. The program will add the figures together in the first line, work out the percentage in line three, even access current exchange rates to convert $75 to British pounds, before adding all four values together to give a total.

Feel free to include text within your calculations, and OpalCalc will usually figure out what you mean

If you remember one or two OpalCalc keywords then you can take the program further still. “As”, for instance, is ideal when you need to convert a mixed set of units into a single measurement system, like “4inches + 75cm + 2metres as cm”.

Or if you place an @ sign at the start of a line then you can take advantage of OpalCalc’s date and time-related maths: @11:00 to 13:51 as minutes, @today – 7 days, @17th August 2012 + 35 days + 8 hours, and so on.

And if you’re comfortable with maths anyway then you’ll be pleased to see that OpalCalc has a lot of functions you can use here, covering trigonometry, statistics and more (click the Pi icon to the right of the toolbar to view the full list), which you can extend further with your own variables, functions and more.

One potentially significant problem here is that the free demo version of OpalCalc won’t perform calculations on more than five lines. Which means you’re not going to be able to create lengthy spreadsheet-like lists.

With a little thought, though, there’s still a considerable scope here for getting a lot of work done. And if you do want to upgrade, it need not be as expensive as you might think, because the author is currently allowing users to pay whatever they think OpalCalc is worth (the suggested range for home users is $5-$25, but the actual payment is up to you). Click “Upgrade OpalCalc” from the main menu to find out more.