Not so with UnitCalc. It's a Reverse Polish Notation calculator which does all arithmetic with the numbers and the units. Many mistakes will be caught immediately when the units in your answer are not what you expect; other mistakes will be avoided entirely, since you never need to shift decimal places (for example, when dividing m^2 by mm*cm). Moreover, UnitCalc is fully configurable -- you define what units you like to use. It will even do American units, if that's what you prefer.
| You Enter: | UnitCalc Displays: | What's Going On? |
|---|---|---|
| 300 g | 0.3 kg | per our preferences, show mass in kilograms |
| 5 m^2 | 5 m^2 0.3 kg |
puts 5 square meters on the stack |
| * | 1.5 m^2 kg | multiplies top 2 elements of stack, with units |
| clear | empties the stack | |
| j | 1 j | puts 1 joule on the stack |
| w | 1 w 1 j |
puts 1 watt on the stack |
| off | 1000 m^2 sec^-3 g 1000 m^2 sec^-2 g |
turns off unit conversion; shows values in base units |
| / | 1 sec | divides (1 j / 1 w), leaving 1 sec on stack |
| 10 v | 10000 m^2 sec^-2 g c^-1 | puts 10 volts on the stack in base units |
| on | 10 v | resume showing in preferred units |
| 2 ohm | 2 ohm 10 v |
puts 2 ohm on the stack |
| / | 5 amp | divide (an application of Ohm's Law) |