Errors and omissions: Are you better at mathematics than Jeremy Clarkson?

Extra care is required when one of our writers makes fun of someone for getting things wrong. On Monday, we mocked Jeremy Clarkson's grasp of averages. "The average adult sends 200 texts a month," the sage of The Sun had written. "Plainly, they never spoke to my eldest daughter about this." Our columnist explained: "If your eldest daughter sends 1,900 texts per month while nine non-relatives each send just 100, the average is not 1,900 but 200." Except that it is not. As Laura Newton, a reader, pointed out, if they "each" send 100 that makes 900, plus 1,900, which is 2,800. So the average is 280. The point is awarded to Clarkson.

Wind up: A fine polemic against wind farms on Tuesday included this: "No one argues that turbines produce power." On the contrary, everyone accepts that they produce power. The argument is about whether the cost, in money and industrialisation of the countryside, is worth it. As Sebastian Robinson pointed out, what we meant was the opposite: "No one disputes that turbines produce power."

Forced to be free: Sara Neill writes to say that, as a girl, she used the phrase "for free" with a giggle, "knowing it was wrong". Imagine her horror, then, when she saw our headline on Wednesday: "Big rise in number of graduates forced to work for free." As she says, "You do not do or receive something for free. Either you do or get it for nothing, or it is free."

I would also quibble with the word "forced". In the same way that George Galloway describes recruitment to the armed forces in Glasgow as "economic conscription", this is exaggeration for effect. Some people on benefits are required to take work placements for no additional money, on pain of possible cuts in benefit, and even that is not "forced".

This news report was not about them, but about the 23 per cent rise in graduates taking unpaid work. That is bad enough – and some of it may be against the law – without the bad grammar and the overstatement.

Touch of hellfire: I am also grateful to Ms Neill for drawing attention to our report yesterday that said an Olympic shooter "fell pregnant". It is a horrible old-fashioned phrase, connoting sin, which we should stop using.

Paper over the split: My view is that split infinitives do not matter, but they are easy to avoid and so there is no need to irritate the pedantic minority who find them irritating.

Also, a split infinitive often warns of other problems. Take this, from our report on Thursday of the Scottish government's decision to legislate for gay marriage. If the Bill passes, we said, "gay couples would be able to legally wed in both civil and religious ceremonies as early as 2014". There would be nothing wrong with "to wed legally", except that "wed" is journalese. However, the split infinitive arises from the phrase "be able to", which is a telltale way of papering over a weakness in a sentence. Also, "both" is redundant. So this would be better: "Gay couples could marry legally in civil and religious ceremonies as early as 2014."

Guy Keleny is away