Steve Ballmer's back in the numbers game, this time predicting sales of Windows 8 and Windows Phone 8 kit to draw in application developers.

Ballmer is reported to have claimed at the event that "close" to 400 million Windows phones and tablets will be running Windows Phone 8 and Windows 8.

He didn't say when, though.

Appearing at Nokia's unveiling of the 820 and 920 Wednesday, Ballmer is quoted as saying:

We should see close to 400 million new devices running Windows. Lumia and Surface: those devices represent the single largest opportunity for software developers, in the biggest community. The next app developer to hit it really really big will do so on Windows.

Microsoft hasn't given any numbers on what it expects in terms of sales for Lumias running Windows Phone or for its Surface Ultrabook-cum-tablet running Windows 8.

Ballmer has said before he expects 375 million Windows PCs to be sold over the next year.

Of these "a few million" might be Surface devices, according to Ballmer. Microsoft's chief executive, though, seems to be playing down numbers so his company isn't seen to be treading on the toes of those who traditionally put Windows into the market: the PC makers.

A "few" is a subjective term that depends on the context. In the context of 10, a few might be six. In the context of 375 million that could be 50 or one hundred million.

As for phones, Nokia is being credited with having sold seven million Lumias, with four million in the last quarter and two million in two quarters before that. It's almost a year since the first Lumia appeared, so even if Nokia doubles its sales a year from now, that would still just be 14 million.

Here's some context: Samsung claims 20 million Galaxy SIIIs have been sold since its introduction three months ago. One million iPhone 4Ses were sold in the 24 hours after launch in October last year.

What Ballmer is trying to tell software developers is that, combined, Surface and Nokia can outship the entire PC market for one year. Admittedly, that's a market whose sales are in decline while smartphones have been outselling PCs, with devices in double-digit growth mode.

However, by Ballmer's own admission – or claim, at least – Surface numbers will be kept low. Even with some positive thinking on Lumia sales it's hard to see how Ballmer's numbers amount to anything more a headline figure.

It's a number intended to snare apps writers, exactly the group of people Microsoft needs next to actual customers. These people will write the kinds of apps that Microsoft hopes would attract customers to its platform: another Facebook or Farmville code jockey with business aspirations.

Microsoft wants a repeat of one of the factors that helped propel Windows in the 1990s. Back then the focus was the business not the consumer, and Microsoft through the Microsoft Developer Network under Tod Nielsen recruited software shops big and small, turning them into a standing army of Windows ISVs.

Microsoft needs these types to build apps once again, this time to help Windows hit and break the 400 million barrier. It will achieve 400 million eventually, just not yet on the numbers we're seeing. ®