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Challenge 10B – the second breakthrough

I am making a big assumption here, but I think it it is worth it. Always best to try something rather than just stare at the cipher text, so here goes: With the digits 4-9 on the bottom row the only ways a plaintext pair can contain one of them is either:

a pair XY where both are in the bottom row

a pair XY where both are in the column containing the digit

a pair XY where one of X or Y is in the bottom row.

But digits are very rare in texts, and might not appear at all, so it is most likely that any appearance of a pair containing 4,5,6,7,8 or 9 comes from a pair XY that both lie in the same column as that digit!

It isn’t much, but it is a start, and if we also guess that the most common digraphs in the cipher text represent the pairs TH and HE (the most common digraphs in English) then that might be enough to start to break this cipher.

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