This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.

When using the modulus, if a<b, then a%b = a. But why, if a is negative, does -a%b = -a? According to the division algorithm, the remainder r must be >= 0 and <|b|.