Brain Teaser: Noughts and crosses

From The Sunday Times, 23rd December 1956 [link]

Each square is to be occupied by either a nought or a cross.

The cross (or x) stands for one particular digit which you may discover for yourself.

No light begins with nought.

The following clues give the prime factors of the various lights, each letter representing a different prime:

(I) abcd
(II) a²b²ef
(III) ab²gh
(IV) abij²k
(V) a²bejl
(VI) ab²ikm

(i) ab²ijkm
(ii) a²beij²k
(iii) ab²mnp
(iv) a²bcde
(v) abijkl

This is one of the occasional Holiday Brain Teasers published in The Sunday Times prior to the start of numbered Teasers in 1961. Prizes of £5, £3 and £1 were offered for the first 3 correct solutions.

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