Scunthorpe striker Paddy Madden scored twice as Graham Alexander's side eased to a 4-0 Sky Bet League One win at promoted Plymouth.Madden followed in his own shot, which had come back off the crossbar, to make it 1-0 in the 27th minute following Josh Morris' pinpoint cross from the left.Madden doubled his tally in the 68th minute, diving to head home Duane Holmes' pacey near post cross, after the substitute made room for himself with a dazzling run down the right.Tom Hopper made it 3-0 in the 76th minute, diverting Morris' incisive ball down the left with the deftest of touches to convert off the inside of a post from just inside the area.Morris was rewarded for his part in two of the goals, sweeping home United's fourth goal in the fourth and final minute of stoppage time.Plymouth were reduced to 10 men in first-half stoppage time when Antoni Sarcevic saw red for an off-the-ball incident.The home side introduced new on-loan Celtic target man Nadir Ciftci and the debutant was denied when his 15th-minute header was saved on the line by Iron keeper Matt Gilks.