Size: 144 cells
Mathematical. The grid consists of two identical 11 × 6 grids, side by side, linked by a 12-cell 1ac. Except for this last entry, clues are presented in pairs, in no particular order, each giving a “word” built up arithmetically from letters representing numbers. All grid entries are perfect squares. Solvers must deduce the values of 20 letters, in the range 1–20, with no repeats. This can be done except for two letters. Both of the two possibilities that remain lead to viable entries at 1ac. Solvers must therefore analyse the two bottom entries, which are unclued. Factorisation of these provides several possible words, from which LEFT and RIGHT stand out, thereby fixing the two final values and the order of the two sub-grids.
G Haddow (Croydon)
David Meek (London N8)
Dr T R Poole (Beeston, Nottingham)