#23456789_123456789_123456789_123456789_12
perl -nlE'65^unpack"%c*","?"x30&uc or say'

##</code><code>##

#23456789_123456789_123456789_123456789_1
perl -ple'$_ x=65==unpack"%c*","?"x30&uc'

##</code><code>##

#23456789_123456789_123456789_123456789_
perl -pe'$_ x=75=~unpack"%c*","?"x30&uc'

##</code><code>##

#23456789_123456789_123456789_1234
perl -ple'$_ x=1==unpack"%6c*",uc'
perl -pe'$_ x=11==unpack"%6c*",uc'

##</code><code>##

#23456789_123456789_123456789_1
perl -ple'$_ x=1==unpack"%5c*"'
perl -pe'$_ x=11==unpack"%5c*"'
perl -nlE'1^unpack"%5c*"or say'
perl -nE'11^unpack"%5c*"or say'