Your Mac Life’s Shawn King sent along a note from listener Tom Durkin, who found an anomaly with a recent version of Calculator. Tom writes:
I just noticed a really embarrassing bug under 10.4.5 (which doesn’t happen under 10.4.2).
If you set Precision (from the Calculator View menu) to 2, it should mean “round every displayed result to two decimal places, that is to the nearest penny,” and that’s what it does under 10.4.2. But under 10.4.5 it means “round the result to two significant digits.”
For example, under 10.4.2: 2752 - 1 = 2751
But under 10.4.5: 2752 - 1 = 2800 (since 2751 rounded to two significant digits in 2800)!
Aside from delivering the punch line to the hoary “Doc, it hurts when I do this!” I’ll mention that the bug is specific to the version of Calculator (version 4.0.4) that ships with the latest couple of Tiger updates. I whipped out an older version of Calculator (version 3.2.1) and it worked properly.
I’m sure Apple is all over this one and a fix is imminent. In the meantime, choose something like 10 in the Precision submenu to avoid the problem, use the Calculator widget, or grab a more powerful calculator—James Thomson’s excellent $19 PCalc comes to mind.