Oxygen?
It has to be oxygen.
"NBFHe0C"
N = Nitrogen
B = Boron
F = Fluorine
He = Helium
C = Carbon
0 = Missing = Oxygen (is among them in the periodic table)
If the 0 is just a 0, and the rest are elements on the periodic "table", then we get 759206.
If the 0 is Oxygen, then we get 759286.
Are either of those numbers meaningful?
Note that the original clue (which was announced to accidentally be "wrong" did not have any lower case 'e'. In that case, it would seem that 'H' would be hydrogen, except that there aren't any elements that are simply represented by a capital 'E'. If we assume that the "wrong" clue meant for HE to be helium, and we assume that 0 is just a 0, then the original "wrong" clue would have ended up with: 880262
Interestingly, all of these are 6 digit numbers (759206, 759286, and 880262). Of this list of numbers, 759206 seems most likely to be correct, but I'm not sure what meaning that number carries.
I'm also noticing that only the single digit elements were used (for example Re could have been used instead of NB). This would explain why a 0 needs to be used, since there is no element with an atomic number of 0. This would seem to imply that each number stands on its own. Perhaps it is 6 single digit numbers rather than a single 6 digit number? 7,5,9,2,0, & 6