How to ask a question to get an ordinal number answer

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How to phrase an asking sentence that must be answered with an ordinal number?
Framing a question whose answer is an ordinal number

Given that I want to know Barack Obama is the 44th President of U.S.A, how can I frame a question like:

The how manyeth president is Barack Obama?

Answer

I'd go with the following structure:

Q: Where does Obama fall in the sequence of US presidents?

A: [He's the] 44th [president].

This reflects similar usage when discussing, for instance, rankings:

Q: Where did Harvard fall on the U.S. News & World Report list this
year?

A: 2nd.