(FORTUNE Magazine) – Challenge in the last issue: to figure out, with the help of 13 clues, which of ten Senators was the ''most liberal'' -- i.e., which had the highest total when you added the scores assigned each of them by ADA, COPE, and the ACLU. Clue 1 stated that the winner's total was 277. The puzzle can be solved by demonstrating that only one of the ten could possibly have attained exactly 277 points. CRANSTON can be ruled out as follows. We know he got an 87 from the ACLU ( 3). We also know he had a COPE rating four points lower than Kerry of Massachusetts ( 10). Since all Kerry's scores were divisible by 5 ( 10), the final digit of Cranston's COPE score must be 6 or 1, and the final digit of his ACLU+COPE subtotal must be 8 or 3. Next we observe that his ADA score has to be divisible by 5 ( 4), i.e., the final digit is 5 or 0. So now the problem is to add two unknown numbers, one of them ending in 8 or 3, the other ending in 5 or 0. Experimenting with all four combinations, we observe that none of them yields a number with a final digit of 7. Ergo, Cranston could not have had a total score of 277. Take him away. KENNEDY can also be ruled out. We know that his ACLU score was 88 ( 3 and 6). We also know that his COPE score was five points lower than that of Sarbanes ( 6). Since the two top COPE scores are 100 and 98 ( 7), Kennedy's highest possible COPE scores are 95 and 93. Since he did not get an ADA score of 100 ( 2) and all ADA scores are in multiples of 5 ( 4), his highest possible ADA score was 95. Adding his ACLU score to his highest possible scores on the other lists, we get 88+95+95=278, which is one point too high. His next-highest possible score, which assumes a 93 from COPE, is 276 -- one point too low. (In fact, his score was 276 and he came in second.) MIKULSKI and SARBANES, the Maryland contingent, can be ruled out much more easily. We know their ACLU scores were, respectively, 77 and 70 ( 9). With 77, Barbara would need two 100s in the remaining rankings to reach the magic 277, but we know that's impossible for her since you have to be from New England to get 100 out of ADA ( 2). So no dice for the Marylanders. Incidentally, they were the ones who got 100 (Barbara) and 98 (Paul) from COPE. MATSUNAGA and INOUYE are also fairly easy. We know that all their scores were within five points of one another ( 11). Because ACLU does not go above 88 ( 3) and ADA has only multiples of 5 ( 4), their highest possible ADA and COPE scores would be 90 and 85, although we have no way of knowing which would be which. It doesn't matter: The highest possible total for either Hawaiian is a mere 90+88+85=263. SIMON gets shot down with the Hawaiians. Clue 12 tells us that he had a lower ADA score than Matsunaga. We already know, from the preceding paragraph, that Spark's score cannot exceed 90, so Simon's cannot exceed 85. With an ADA score of 85 and a maximum ACLU score of 88 (subtotal: 173), Paul has no way of stretching to 277. LEAHY of Vermont doesn't make it either. Since he's from New England, he could have (and in fact did have) an ADA rating of 100. He also could be among those who got the maximum of 88 from the ACLU. So he could hit 277 if he had an 89 from COPE. However, we learn from 8 that his COPE score was ''several'' points lower than Inouye's. Several means at least three. Since Inouye could not have got more than 90 from COPE, as previously explained, Leahy's highest possible COPE score was 87, and he necessarily comes up short with a maximum of 275. KERRY's problems begin with the fact that Kennedy had a COPE score five points lower than Sarbanes ( 6). This means that Kerry and Kennedy cannot be the two same-state Senators who got the top COPE scores of 100 and 98 ( 7). And since all of Kerry's scores are multiples of 5 ( 10), his highest possible COPE score is 95. How about his ADA score? We note that it is five points lower than Cranston's ( 10), and since Cranston could not have got an ADA score higher than 95 (remember: only New Englanders can get 100), Kerry's ADA score cannot top 90. His ADA+COPE subtotal cannot exceed 90+95=185, so even if he was among those receiving the top ACLU score of 88, he would still fall short at 273. So -- CLAIBORNE PELL has to be it. The only information given about him is that he got an ACLU score of 85, which proves nothing. He also happens to have got 100 from ADA (he was the other New Englander) and 92 from COPE. Which adds up to 277.