The UK designed Raspberry Pi microcomputer, which has triggered all sorts of creative single board computing projects — most recently being repurposed as the heart of a DIY computer designed to help kids learn to code — continues to sell in far greater quantities than its creators ever imagined.

Sales of low cost, open source microcomputer have now passed 3.8 million, according to the Pi Foundation. And while that pales in comparison to sales of consumer electronic devices such as smartphones, it’s a seriously impressive figure for a bare chunk of electronics, especially given the creators of Pi envisaged selling as few as 10,000 boards over its entire lifetime.

In the event the Pi shipped just over a million in its first year on sale, and some two-and-a-half years of sales are evidently continuing to track upwards. This summer the Foundation released a beefed up version of the model B Pi, called the B+, which keeps the same $35 price tag but improves aspects of the design to support richer use-cases, such as adding in more USB ports and expanding the number of GPIO pins. A more capable Pi is evidently helping to keep Pi sales tracking up.

For more Pi goodness, join TechCrunch at Disrupt Europe in London on Tuesday, October 21 at 2:50 p.m. where we’ll have co-founder Eben Upton on stage to chat about the new B+ boards and talk more generally about the road ahead for Pi — now that it’s no longer a road less travelled.