According to The San Jose Mercury News, Milner bought the property in Los Altos Hills with a combination of cash and pre-IPO Facebook shares, from Fred Chan, the founder of ESS Technology.
Since we're hard pressed to think of a scenario where having a calculator and card reader on hand would be essential to your well being -- especially considering that handy "Calculator" app that comes pre-loaded on most every computer these days -- it's difficult to postulate when this awkward combination of gadgets would actually come in handy.