1) I wonder how you came up with that.
Do both the following sentences convey the exact same meaning as the one used above? Are they both grammatically correct?
2) How you came up with that, I wonder.
3) How did you come up with that, I wonder.
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Sign up to join this community1) I wonder how you came up with that.
Do both the following sentences convey the exact same meaning as the one used above? Are they both grammatically correct?
2) How you came up with that, I wonder.
3) How did you come up with that, I wonder.
The third one isn't grammatically correct. If you don't have a question mark (and thus don't have a question), you can't use the subject–auxiliary inversion.
How you came up with that, I wonder.
Is correct, and might have a slight change of tone. To me, it adds disbelief and a somewhat condescending tone to the sentence by emphasizing I wonder at the end of the sentence, after a comma.
For the last one, you could say:
How did you come up with that? I wonder.
Which, to me again, conveys a similar tone of condescending disbelief.