Chloe Brink
1. You need to find the underlying rule that unites all numbers in each set but one.
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2. In this specific puzzle, the number 7 plays a significant role.
(PARTIAL SOLUTION FOLLOWS)
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3. In the first set, all numbers are multiples of 7, except for one.
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4. In the second set, the digits in each number add up to 7, with one exception.
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5. Combine information from sets 1 and 2 to solve set 3.
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6. In the third set, all numbers can be sums of the digits of multiples of 7, except for one. In other words, 21 (2 + 1 = 3), 14 (1 + 4 = 5), 42 (4 + 2 = 6), etc. There is no multiple of 7 under 100 where the digits add up to 4.
(SOLUTION FOLLOWS)
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7. Select 64, 79 and 4, then turn the dial.