So Google have come up with a number, and it's big. Thanks to the blistering pace of technology, of course, its claim that there are precisely 129,864,880 books in the world will already be just that little bit out of date – but it's enough to set you thinking. How many of them are any good? How many of them have never been read by anybody other than their author? How many of them are available on the Kindle?

The number itself, naturally, is open to dispute. On the Google Books blog, "software engineer" Leonid Taycher goes into gnarly detail about how they've arrived at it, beginning with the question "what is a book?" and going on to investigate issues of duplication, the reliability of sources and the exclusion of "non-books" (microforms, maps, t-shirts with ISBNs – there are around 1,000, apparently). It seems that they've given lots of thought to the matter, at any rate, but what we'd like to know is a much more homespun sort of number. How many books can you, personally, put your name to?

Counting the books I've got at home is complicated because I'm not there right now, and neither are most of my books (long story), but right here, right now, "filed" on the desk, I've got 46 – though I swear that at least three of those have nothing to do with me. In the cupboard across the way I've got about another 60, and there are probably a bunch more waiting for me in the post room, so even on this small scale, when we try to come up with a figure, we run into problems. But nevertheless that's what we want to know: if Google has 130m books, how many do you have?