Updated 4:05 am, Saturday, April 16, 2016

Here’s a fun game you can play when you’re contemplating the homes and estates of the Bay Area’s super-rich: Check out one of the listings for one of the region’s higher-priced properties. For instance, the $42.8 million beauty at 47 Camino Por Los Arboles in Atherton 94027 — the nation’s most expensive ZIP code.

The agents for the home, which is apparently the most expensive currently listed in the Bay Area, describe it as “an Italian villa … designed with Silicon Valley living in mind — a home for families of all sizes with venues for entertaining and myriad options for recreation and well-being.”

Like many of the most expensive homes in the region, it sits on a nice-sized parcel — an acre and a half. The main residence is 16,468 square feet, with six bedrooms, six full bathrooms, four half-baths, half a dozen fireplaces, a pool, a 3,000-bottle climate-controlled wine cellar, an 11-seat home theater outfitted with Dolby’s state-of-the-art Atmos sound system and an elevator to assure access to all of the above.

Quite a dump.

But pondering the presumed wonders of inhabiting such a residence — I think my current life is big enough to occupy a clothes hamper in the maid’s quarters — isn’t the fun part. No. That comes when you calculate the payments a mortgage on this mansion might require.

Assuming a 20 percent down payment — $8.56 million — and a 3.7 percent interest rate on a 30-year mortgage, your monthly payment would come to something like $200,000. Now ask yourself, “How much did I gross last year?”

See? Wasn’t that fun?

Of course, the actual purchaser of 47 Street Through the Trees probably won’t be borrowing money to buy it unless there’s a big tax advantage in it. Which brings up a few interesting points about the 38 or so properties, sold $12 million and up, reported as having changed hands in the nine-county Bay Area since January 2015:

Meet Your Neighbors, the LLCs: The purchasers of 27 of the 38 properties are listed as LLCs, or limited liability companies, set up on behalf of the wealthy individuals who bought the homes. LLCs afford buyers several advantages: They maintain buyers’ privacy, since it’s very difficult to ferret out exactly who’s behind an LLC. These arrangements can also allow wealthy homebuyers to shield their fortunes from liability claims related to their property. But according to an extensive New York Times investigation published last year, LLCs have been used to shield the identities of money launderers, mobsters and other nefarious types who have invested in high-end Manhattan real estate.

These Places Are Pricey, but …: Yes, it’s mind-blowing that regular oxygen-breathing human beings living right here among us plebeians are pouring tens of millions of dollars into their swank digs. But the residences on this list are not even remotely close to the most expensive residential property in the Bay Area. That honor — is it an honor? — would almost certainly go to the Woodside estate of Oracle founder Larry Ellison. The cost of that property, modeled on a Japanese imperial villa, has been estimated at $200 million.

The Wealthiest Nabes: No news here, really, but still striking that so many of the most expensive homes are so tightly packed. Eleven of the properties on our list are in Atherton, a Peninsula community of about 7,000 where you don’t live (the median home price there, according to Forbes: about $10.6 million). Another 11 of the residences we list are in San Francisco. Nearly all of those are in a tight cluster in Pacific Heights, including three on the 2900 block of Vallejo Street and two more on the 2700 block of Broadway. The geographic outlier in the group is the Round House, a Berkeley Hills home sold for $20.5 million earlier this year by tech entrepreneur Robert Felton. It’s the only property we found in Alameda or Contra Costa county to command an eight-figure price in the last 15 months.

A Word on Our Sources: Our list was built from and cross-checked using a variety of sources, including the San Francisco Chronicle Bay Area home sales database; online real estate sites including MLSListings.com, Zillow, Redfin, Estately.com, SF Blockshopper, and PropertyShark; print and online publications including the San Francisco Business Times, Curbed San Francisco and SocketSite; and public records from San Francisco, San Mateo, Marin and Santa Clara counties.