Final answer:
The excerpt "Wrong!" best conveys the author's purpose to entertain.
Step-by-step explanation:
The excerpt from The Number Devil that best conveys the author's purpose for writing to entertain is:
"Wrong!" the number devil shouted, his mustache quivering, his eyes bulging, and his face turning red with rage.
This excerpt demonstrates the author's intent to entertain readers through the use of dramatic dialogue and vivid description of the number devil's reaction.
Learn more about purpose of writing in The Number Devil