"Holy Jeepers, Batman!!" cried Robin, "What do we do now?!"
"Not to worry, Robin" Batman said calmly, "The answer to your question can be found in this riddle left by the Riddler. One plus One equals blank."
"Whatever could it mean, Batman?"
"It must be in plain sight, Robin. What does One plus One mean?"
"One plus One... One plus One... I can't think of a thing!"
"Yes, the Riddler has left a difficult riddle this time around. Come, Robin. To the Batcave! The computer will help us with this problem."
"Good idea, Batman!"