After a tough loss at home, the Steelers traveled to Cincinnati to take on the Bengals.  After a scoreless first quarter, the Steelers were the first to score in the 2nd when Ben Roethlisberger found Heath Miller on a 1-yard TD pass for a 7-0 lead.  Afterwards, the Bengals would tie it at 7-7 when Andy Dalton hooked up with Jermaine Gresham on a 10-yard TD pass.  They took the lead when Dalton ran for a 20-yard TD himself for a 14-7 game.  The Steelers wrapped up the scoring of the first half coming within 4 when Shaun Suisham kicked a 22-yard field goal for a 14-10 game at halftime.  The Steelers retook the lead in the 3rd quarter when Roethlisberger found Le'Veon Bell on a 10-yard TD pass for a 17-14 game.  However, the Bengals took the lead back when Dalton found A. J. Green on an 81-yard TD pass to make the score 21-17.  In the 4th quarter, it was all Steelers when they scored 25 consecutive points:  First coming within 1 as Suisham kicked a 44-yard field goal for a 21-20 game followed by 3 straight touchdowns:  Le'Veon Bell ran for a 13-yard TD with a successful 2-point conversion as they retook the lead 28-21, followed by Roethlisberger finding Martavis Bryant on a 94-yard TD pass to move ahead 35-21 and finally Bell ran for another TD from 22 yards out for the eventual final score of 42-21. With the win, the Steelers improved to 8-5 with their odds of winning the AFC North and playoff hopes looking really bright.
Question: How many points did the Steelers win the game by?
Answer: 21