This unusual math problem is from a hilarious book that
Jonathan Caws-Elwitt recommended,
Three Rousing Cheers for the Rollo Boys by Corey Ford:
"Harry! Tom!"
"Dick! Tom!"
"Tom! Harry!"
"Stop!" cried Dick suspiciously; and, taking out a sheet of white paper, he wrote down: "Harry! Tom!" "Dick! Tom!" and "Tom! Harry!" He then added them together and divided through by Tom.
Can you guess the result?
Answer: "The result is Harry and Dick," he said seriously. "Tom cancels." (The answer is in black text on the black background. Highlight it to view.)