Card Set Estimate

Can someone explain to me what this means in Ajax Bob? It doesn't seem to match the number of armies upon the next cashing in of cards and it's not a percentage, so i'm confused what the number mean? My guess, thus far, is that it's some sort of number out of ____ set up where the odds are, say, 8.2 out of ten let's say, but I don't know the number out of is for this to make any difference. Please help!
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