DB<36> $num = 1e12

  DB<37> $log10 = log($num)/log(10)

  DB<38> p $log10
12                              # Looks good, right? 
  DB<39> p $log10 % 3
2                               # surprise!
  DB<40> p int($log10)
11                              # Oh one of Perl's DWIM show Float as Integer
  DB<41>