As a college chem professor, the reason for this is nearly always cheating.
“Hmm, you got the right answer with the wrong method, and your friend that you sit next to every day used the right method and got the same exact answer as you, down to the rounding? Haha, what are the odds??!?”
Zero. The odds are zero (within sig figs).
I tried this in university. I knew the right answer but not how to get it, so I made a “mistake” in the calcs. It was circled with “something’s not right”. No marks.
We had a formula once that you could aproach from two ways. So I went backwards once I couldn’t figure out how to continue. In the end I still didn’t know how to get from x to y but this was a small enough step the corrector would know surely.
“…and after I completed the formula, I used my calculator to get the answer.”
