I read, with interest, the article “He can work it out” (TES Friday, May 5) about Lawrence Potter’s book Mathematics Minus Fear. However, the three lines of mathematics shown on the blackboard picture contain two minor errors and one significant error (were these deliberate?). These errors are: (i) second line; the term “dx” should not be under the square root sign (minor error) (ii) third line; The term “dx” has been missed out in the integral (minor error) (iii) third line; squaring the expression in the square root of line two, which then appears in line three, has been carried out incorrectly (significant error).

Three errors in three lines is not unusual these days!

Paul Lock

The Cottage

92 Ashby Road

Burton upon Trent, Staffs

Editor’s note: the image of the blackboard, reprinted above, came from a picture library, not Lawrence Potter’s book. Thanks to both readers for pointing out the errors.