What jersey number did Mike Singletary wear with the Bears?

What jersey number did Dick Butkus wear with the Bears? What position did Mike Singletary primarily play? Mike Singletary is best known for playing with which NFL team? Which college was Mike Singletary playing for when he entered the NFL? What position did Jack Lambert primarily play? Jack Lambert is best known for playing with which NFL team? Which college was Jack Lambert playing for when he entered the NFL? What jersey number did Jack Lambert wear with the Steelers?