Just how far of the mark that initial guess was became clear at the end of October, when the two millionth Raspberry Pi board was sold.
Writing on the Raspberry Pi Foundation's website, Liz Upton, head of communications for the foundation, stressed how far it had come since picking up the first pallet of 2,000 boards in February 2012.
"Getting the news about the 2,000,000th Pi at the end of last week, it struck us that every single Raspberry Pi in that pallet represents 1000 of the Raspberry Pis that are spread around the world today.
"We never thought we'd be where we are today when we started this journey."
Upton said the rate at which boards are selling is increasing, while it took almost one year to reach one million sales it took about eight months to hit two million.
The credit card-sized Raspberry Pi was designed as a low-cost, portable board that kids could plug in and start coding wherever they were.
By making it simple for children to program, the foundation hoped to inspire the next generation of programmers, similar to how many of today's UK developers cut their teeth on the BBC Micro. With the two million boards sold the Pi has now outsold the computer that inspired its creation, as just over 1.5 million BBC Micros are estimated to have been sold.
Raspberry Pi machines have found their way into schools and universities, with the foundation giving out 15,000 free boards to schools, but the boards have also proven to be very popular among the wider hobbyist community, who set about using the boards in projects ranging from robotics to home automation.