Grep for character with uppercase and number

Hello,

I would like to be able to extract the uppercase character or the uppercase character which has a number, here is my grep which works for the uppercase characters, but I cannot manage to capture the uppercase character and having number, I tried

grep " [A-Z]\+" -x
text.txt
#############
between
for
TAR
torsions:
##########
Answer : TAR
It’s ok

But
grep " [A-Z]\+" -x
grep " [0-9]\+" -x
grep “[A-Z]\+ |[0-9]” -x
grep "[A-Z]\+ |[^0-9]{1} " -x

txt2.txt
###########
between
for
P1A
torsions:
###########
Don’t capture P1A,
I don’t want to do the : grep “P1A” , because I have several files to process in series, with the same problem

Best,