How much do you remember from the classroom?

'SO, WHAT is osmosis?" Picture the scene: the question was posed innocently enough – just in passing, in fact – over Sunday lunch with friends. After a long gossip about an irritating colleague who was forever saying "as if by osmosis" (for example, "As if by osmosis I was supposed to know that, just because she said she didn't want to have a drink with me that one time, I should never ask again") we were left to work out what it actually meant.

The concept of the annoying workmate came to us easily enough, but of the four graduates sitting round the table, not one of us could explain osmosis.

A quick trawl around the internet and we found an explanation that we could understand (just) – but I've got to confess that since then I've forgotten it again. You see, it's one of those bits of information I learned at school, which dropped easily enough into my fresh young brain but has since been forgotten. A similar fate has befallen such facts as how many elements are in the periodic table (117 in case you're interested – I had to look it up again) and how to do long division (oh, the shame).

What I didn't realise was that my ignorance is far from unusual, if sales of Caroline Taggart's I Used to Know That (helpfully subtitled Stuff You Forgot From School) are anything to go by. The book, a seven-chapter wonder that covers everything from the briefest synopses of Shakespeare's greatest plays to the laws of thermodynamics and basics of geography and maths is described by Taggart, below right, as a "loo book" – something lightweight to dip in and out of. But its popularity suggests that it's striking a chord with people – and that I am not the only one planning to keep it on my desk to avoid any intellectually embarrassing moments, such as being asked how to solve a simultaneous equation.

The book's popularity places Taggart in an illustrious company that also includes Lynne Truss (Eats Shoot and Leaves), Judy Parkinson (I Before E Except After C) and Jacquie Wines (Mondegreens: A Book of Mishearings). As writers of amusing but useful books, they remind us it is good to know how to use an apostrophe correctly, that remembering the colours of the rainbow is easy with a mnemonic and that we're not the only ones who mishear song lyrics.

There's plenty to suggest that men have a greater appetite for trivia than women. Mark Mason, writer of The Importance of Being Trivial: In Search of the Perfect Fact, goes so far as to suggest that trivia not only provides a way for men to bond with each other (endless chats about engines and football transfer fees come to mind) but that they have "systemising" brains which demand facts rather than "empathising" brains that women have.

Taggart, a self-described "trivia person" is not so sure of that distinction. "I used to say that, when it was fashionable, nobody would play Trivial Pursuit with me," she says with pride. She is a pub quiz queen from a family of crossword fans, encouraged by her Scottish parents to "look stuff up, to learn for learning's sake".

And aren't there more women writing the kind of book that she has than men? "I think that's true," she says. "Are we more nitpicky, perhaps?"

Pedant or not, Taggart, educated in New Zealand before moving to London where she still lives, worked in publishing for 30 years and has been stunned by the success of her book. She puts it down to nostalgia to some extent but she's been surprised by the topics that have interested readers.

"What has struck me most is the things that appeal to people the most are the things they used to hate," she says. "I loved writing the English and history chapters because those are my subjects. I was expecting people to pick up on summaries of Dickens or bits and pieces of English language but no, people say it's the moment that they see those equations a+b+c, that's what they love."

Taggart believes the maths chapters are proving a favourite because so many of us felt we were rotten at the subject at school, or simply didn't enjoy it.

"So many of us were so bad at maths, we didn't undertand it at school and we were scared of it," she says. "I now realise that so much wasn't explained to us. I didn't realise for years what trigonometry was about … nobody said, 'And you can go out and measure the height of a tree if you know this.' I don't spend a lot of my time measuring tree heights but a lot of people do. It would've been more interesting if we'd known."

She's right – OK, I haven't often needed to calculate the height of any local spruces, but I have needed to calculate percentages (to work out price reductions in shops), and I've even had to work out how many lovely little Italian glass mosaic tiles to buy to tile my bathroom (where a little mathematical knowledge saved me the horrors of running out half-way through the job, or finding I had bought twice as many non-returnable tiles as I needed). I might have paid more attention in class if I'd known of the practical uses of maths.

Taggart claims another reason books like hers are flying off the shelves is anxiety about memory loss. "Look at the fantastic success of sudoku," she says. "Everybody says 'use it or lose it' about the brain, like any other muscle. So if learning facts like the dates of English kings is going to keep the brain alive, so be it."

Not that she was impressed by an interviewer who, caught up in the excitement of the book, told her that he was off to learn the names of all the kings and queens of England. "I'm afraid I thought, 'Whatever for? You can look them up,'" she says. "He was obviously inspired by the enthusiasm of the moment and wanted to go away and learn these things and somehow nebulously make himself a better person."

And it's a crucial point. It may not make you a better person to know the difference between mean, median and mode, but we still harbour a kind of snobbishness about factual knowledge just as we have about knowing which cutlery to use for what course at a posh dinner.

"I've read Pride and Prejudice 20 times, I love it," Taggart says, "so the idea that someone might not know the names of the Bennet sisters is bizarre to me. But I'm not so arrogant to think that I'm a better person because I remember the names…"

Go on, can you name them?

• I Used to Know That, by Caroline Taggart, (£9.99, Michael O'Mara Books), is available now