Member for 3 years, 4 months
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Yevpatoria, Republic of Crimea, Russia
For Puzzle #1, I'll go with this math style approach For Puzzle #2 and Puzzle #3, my answers would be exactly the same with Dr. Roggia's and Ian Fako's answers.
Using the notation of double factorial: WolframAlpha approves it.
Some users here might find this answer sexist, but unfortunately, it is true. So, my guess is
If the double factorial is allowed, then I propose WolframAlpha agrees that the result is 19.