$var = '09';
$trans = '/3+5';

eval "$var$trans";  # eval gets '09/3+5'
                    # Illegal octal digit '9'

eval $var.$trans;   # eval gets '09/3+5'
                    # Illegal octal digit '9'

eval '$var'.$trans; # eval gets '$var/3+5'
                    # result: 8

##</code><code>##

use Devel::Peek;
$var = '09';
Dump $var;
$var + 0;
Dump $var;
$var / 3;
Dump $var;
__END__
SV = PV(0x2e352a0) at 0x2e24fc0
  REFCNT = 1
  FLAGS = (POK,IsCOW,pPOK)
  PV = 0x2e503f0 "09"\0
  CUR = 2
  LEN = 10
  COW_REFCNT = 0
SV = PVIV(0x254b610) at 0x2e24fc0
  REFCNT = 1
  FLAGS = (IOK,POK,IsCOW,pIOK,pPOK)
  IV = 9
  PV = 0x2e503f0 "09"\0
  CUR = 2
  LEN = 10
  COW_REFCNT = 0
SV = PVNV(0x2ddfc90) at 0x2e24fc0
  REFCNT = 1
  FLAGS = (IOK,NOK,POK,IsCOW,pIOK,pNOK,pPOK)
  IV = 9
  NV = 9
  PV = 0x2e503f0 "09"\0
  CUR = 2
  LEN = 10
  COW_REFCNT = 0