Errors & Omissions: If you're going to mess about with numbers, get them right

Conversion course: One of the most frequent source of mistakes is the mania for converting currency amounts in newspapers. It is often unnecessary, which makes it all the worse when an editor gets it wrong, as someone did in editing Patrick Cockburn's Monday Essay about America's withdrawal from Iraq. He wrote that Iraq's entire military procurement budget for 2004-05, $1.2bn, was stolen.

With helpful intent, someone had inserted £780,000 in brackets after this amount. This understates the theft by a factor of a thousand. My feeling is that people either understand numbers or they don't. If someone understands billions they can probably cope with the idea in their head that a dollar is worth about two-thirds of a pound. In the rest of the article, dollar amounts of $50, $85m and $60bn were not converted. That is fine by me, and avoids the risk of making a distracting error.

Not disinteresting: Tom Mendelsohn's review of Lovebox – it is a pop music festival – on Tuesday said that Paloma Faith went through "her tired, white-bread standards to the disinterest of most". Disinterest is one of those words that has almost given up the ghost. It has a precise meaning, in disinterested, of being impartial – in the sense of not having an interest, or a stake, in the matter in hand. It is now used interchangeably with uninterested, to mean couldn't care less, and by back-formation disinterest means uninterest, except that there is no such word. The trouble is that "lack of interest" would not work in this context. The word for which the writer was searching his mental dictionary was indifference.

Getting our goose: Our Nature Club column on Tuesday was about the culling of Canada geese in New York to reduce the risk of bird strikes to aeroplanes. Andrew Lea writes to point out that it was illustrated with a photograph of "regular farmyard" geese. This is, he says, "as crass as illustrating an article on Shakespeare with a picture of Tom Stoppard on the basis that both are playwrights beginning with the letter S". He has a point.

Lawn makers: On Wednesday, Johann Hari wrote a romanticised comment about the right of self-obsessed so-called protesters to turn a pleasant patch of green opposite the Palace of Westminster into a pile of litter, after the site was finally cleared so that everyone else can enjoy it. He is entitled to his opinion, but it is notable how often the defenders of these supposedly ancient liberties, which were invented in this case nine years ago, get their history wrong. Hari wrote of "protesters being cleared from the lawn of the Mother of Parliaments". England, and not its Parliament, is the Mother of Parliaments.

Good and bad news: We committed a minor sin of editorialising in our report on Thursday of the Deputy Prime Minister's busy day at the office. His remark about the "illegal invasion of Iraq", we wrote, "overshadowed the good news that Mr Clegg brought to the Commons". Well, some people would say that declaring the Iraq war illegal when speaking for the Government was "good news", but they might accept that this was a matter of opinion rather than fact.

The good news to which we referred was that "the controversial family detention unit at Yarl's Wood immigration removal centre in Bedfordshire is to close". Leaving aside the question of whether the word "controversial" is needed, its application to the detention unit should have alerted us to the existence of people to whom its closure is not necessarily good news. Of course, to most readers of The Independent, it is taken as read that detaining the children of people held for deportation is wrong. But there is another point of view, as there is on the legal status of military action in Iraq, which should not be prejudged by our news reporting.