1. He has the least money of all his classmates.

2. He has the least money of all the boys in his class.

3. He has the least money of all the boys in his classroom.
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Are they all grammatical?
Is #1 logically incorrect?

4 answers

Yes, all are grammatically correct, and all three are logically correct. :)
Yes, all three are grammatically correct, and are logically correct.
In Sentence 1, 'all his classmates" doesn't include the subject 'He.' So is this sentence logical or correct?
For sentence 1, another (maybe better) way to phrase it is this ~~> He has less money than any of his classmates.