Why did Tolkien choose numbers 3,7,9, and 1 for the ring-bearers?

If, like me, you've watched "The Lord of the Rings" 10 times or more, you might think there are no more hidden gems or mysteries left to discover in that masterpiece. In fact, there are still many to uncover, especially when it comes to the numbers used in "The Lord of the Rings". My two-part video series reveals some of these secrets. The first part is ready, and you're watching it now. The second part is currently in production. If you enjoy this video, please click the ‘LIKE’ button and subscribe to be notified when the second part is released in the coming months. If you have friends who also love “The Lord of the Rings", feel free to share the link to this video with them. They might find it just as fascinating.
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Part 1.
3, 7, 9, 1.
Why did Tolkien choose these numbers for the ring-bearers?
Were these numbers significant prior to 'The Lord of the Rings'?
Do they possess a magical significance in our world?
What do the Bible, Jewish Kabbalah, Aleksandr Pushkin, quantum physics, 'The Lord of the Rings,' computer technology, and Tolkien’s biography have in common?
What is the SECOND poem in "The Lord of the Rings", featuring the same numbers 3, 7, 9, 1 ?

Part 2 (currently in production)
Did Tolkien treat even and odd numbers equally?
How can you see someone who is wearing the Ring?
Who are the hobbit children living in Minas Tirith?
What is the significance of the 'Magic of Love and Pity' in “The Lord of the Rings” and how does it influence the probabilities of events?

If you want answers to this and other questions related to the magic of numbers in "The Lord of the Rings," simply keep watching. Don't forget to hit the "like" button at the end if you enjoyed the video.