help on programming logic

I had an interview recently, and had a question that I couldn't really answer
They gave me a string (One, Two, Three, Four, Five, Six, Seven.....)
they wanted an output, something like:
Six, two, five, three......
(I'm not 100% sure of the exact strings) They wanted the logic flow I'd use to get the output from the beginning string.
Can anyone help me understand this flow and how it could be programmed?
 
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