Hello all, --"What's the longest you've gone without cooking?' --"Next week will make it three weeks"
If I ask question "what's the longest..." other way "How longest you've gone without cooking?", is it grammatically right?
No, this is incorrect. You would not use this phrase. There are actually only two returns for that phrase (the rest of the hits don't have that exact phrase; both words just appear somewhere on the page). One is a headline, so words have been left out of the sentence, and the other is incorrect.