An example of a particular type of number chain is shown above. The first number must be a positive integer. Each number after the first is the product of the digits of the previous number, so in this case ; ; . The chain stops when a single-digit number is reached. Suppose that in such a chain the final number is 6. Find all possible two-digit first numbers for this chain. (Separate your values with commas)
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Junior Mathematical Olympiad 2006 (2006)
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