Double take

One of my pre-retirement, beer-store acquaintances emailed me yesterday: Are you using Mathematica 8 yet? The copies of Mathematica 4 and 5 on my old machine are Power-PC only, so I can't run them on my wife's Intel. Mathematica 6 is what is collecting the Ruth-Aaron numbers greater than 100 billion. This evening, I installed Mathematica 7 on her iMac and had it running the same program — but starting at 25.2 billion (which is where I was at). Each Mathematica runs at close to 100% CPU because the iMac's "i5" chip is dual-core. Running Mathematica 8 on top of that would only serve to degrade the performance. ;)