OpalCalc is an interesting combination of a scientific calculator and a spreadsheet, which comes packed with features yet remains very easy to use.
At its simplest, you can just start typing in equations on the left-hand side of the window - (10*22)/8, SIN(0.5)*Pi, 2*5/4+(6/7), whatever it might be - while the answers will appear on the right.
And if you know what you're doing 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).
The benefits here aren't just for those already comfortable with math, though. OpalCalc's "as" keyword, 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" (which is 285.16cm, if you were wondering).
Place an @ sign at the start of a line and the program can also carry out 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 even if you're math-phobic, you'll find OpalCalc provides useful features without causing you any pain at all. So for example enter the following, and as soon as you type "total" the sum of your expenses will appear on the right.
$400 for hotel
$50 for my food costs + $75 for Tim
$125 for car hire
$50 to borrow the laptop
And you can extend things further by defining your own variables, functions and more.
There is one significant restriction with the demo version, though: you can't enter more than 5 lines, which could be a major issue. Still, upgrading need not be expensive as the author is allowing users to pay what they think it's worth. Click "Upgrade OpalCalc" from the main menu to find out more.
Version 1.75 changes (Full History):
•Online documentation has been updated to reflect the latest versions of Opalcalc
•RPN (Reverse Polish notation) is now supported! Just start the line with a backslash symbol (\).
•'st', 'th' etc. are now allowed in dates. For example, 'th' in "25th December".
•Pasting text into OpalCalc from programs such as Microsoft OneNote now works correctly.
•More options for when you'll be asked to save your document if you close OpalCalc. "Never", "Always", and anything in between.
•Added cubic mile and cubic kilometre units.
•Spaces in numbers are now supported when used in conjunction with units. This affects countries such as France who may use the space instead of commas (or periods) as a thousands separator.
•Sums such as "(10m/2m)m" produced an error before. Not anymore.
An interesting scientific calculator which thinks it's a spreadsheet, yet is easy (and useful) enough for even the most mathematically-challenged to enjoy.