Calculator posing as a credit card is a great add to any wallet

Hi, I'm Kevin Hall and I'm bad at math. (Boy, does it feel great to finally get that off my chest.) That's why this nifty little solar-powered Credit Card Calculator actually has quite a bit of appeal for me — I could carry it around in my wallet and work out a tip or a grocery bill as I go. It's also a decidedly nice design, looking enough like a credit card that maybe it'd appeal to the spy in all of us, as well.

The best part? It's an easy-to-swallow $6 right now.

Credit Card Calculator, via Better Living Through Design