Well first off when u mentioned the maximum score was 676 I knew that was 26 x 26 and with 26 letters in the alphabet it would be something related to the alphabet.
Also seeing a lot of scores of 20, 25, then your 156.
20 = 10x2 or 5x4 or 20x1.
25 = 25x1 or 5x5
156 = 12x13 or 26x6.
Assuming you did not mix up the letters and A=1 to Z=26 or the reverse A=26 to Z=1, the easiest one to figure out would be 25. that is either AxY, ZxB, ExE or VxV. hmmmmm.
Also seeing a lot of scores of 20, 25, then your 156.
20 = 10x2 or 5x4 or 20x1.
25 = 25x1 or 5x5
156 = 12x13 or 26x6.
Assuming you did not mix up the letters and A=1 to Z=26 or the reverse A=26 to Z=1, the easiest one to figure out would be 25. that is either AxY, ZxB, ExE or VxV. hmmmmm.