chmod-Octal numerical permission for linux

/binary table r,w,x binary octal --- 000 0 --x 001 1 -w- 010 2 -wx 011 3 r-- 100 4 r-x 101 5 rw- 110 6 rwx 111 7 nobody has permission chmod 000 file u+r g+rx o+rx chmod 755 file