N104    F1810
N104    F3810
N104    F810
N104    F305

enter input
read input
cat file | grep $input

N104    F1810
N104    F3810
N104    F810

N104  F810

grep -E "(^|[^0-9])$input($|[^0-9])" < file

$ grep "[[:alpha:]]810" sample.txt
N104    F810

$ input=810
$ grep "[[:alpha:]]$input" < sample.txt
N104    F810

$ input=104
$ grep "[[:alpha:]]$input" < sample.txt
N104    F1810
N104    F3810
N104    F810
N104    F305