--- remainder(other)

    self  other ǳä; r ֤ޤ (divmod)

     r  self Ʊ(ޤϥ)Ǥ
    Ĥޤ
    * self > 0 ΤȤ  0 <= r < |other|
    * self < 0 ΤȤ -|other| < r <= 0
    Ȥʤޤ

        p (13.modulo(4))      #=>  1
        p (13.modulo(-4))     #=> -3
        p ((-13).modulo(4))   #=>  3
        p ((-13).modulo(-4))  #=> -1

        p (13.remainder(4))      #=>  1
        p (13.remainder(-4))     #=>  1
        p ((-13).remainder(4))   #=> -1
        p ((-13).remainder(-4))  #=> -1

    Υ᥽åɤϡ᥽å % ˤäƤޤ

