Mixed doubles:

Slender harm than armed static trot.

The above sentence conceals three connected one-word answers. To find them, all you have to do is to group the six given words into three pairs, then rearrange the letters within each pair. A prize of the new Chambers 21st Dictionary will be awarded to the sender of the first set of correct answers, when we open entries on 21 May. Answers to: Perplexity, The Independent, 1 Canada Square, Canary Wharf, London E14 5DL.

26 April report:

Dates in May that cannot be turned into valid sums under the rules given are 1, 4, 5, 6, 8, 9, 22 and 27. If a decimal point is also allowed, then all except 6.5.97 and 9.5.97 can be done.

Winner: Ben Driver (London)