Matilda is having a hard time, because she wishes her parents weren't so awful.
The only thing that keeps her going is her plot of playing revenge pranks. Soon enough, trouble strikes again.
One night, the family is waiting to have dinner. Mr. Wormwood had what he thinks is a great day at work.
He makes up a story problem for Mike based on what he bought each car for and resold it at.
Mike tells their dad he's great and smart, and Mr. Wormwood boasts about one of his special marketing tools.
When he starts adding it up, Matilda jumps in with the answer.
She did it immediately, in her head.
Mr. Wormwood just tries to ignore her, but Matilda sticks up for herself and asks him to double-check it.
Her dad's horrified to discover that Matilda was right, and promptly accuses her of being "a cheat and a liar." He says that Matilda must have sneaked over to see the answer, which he'd written down, but she tells him that it wasn't physically possible.
Then, Mrs. Wormwood interrupts everyone, coming in with their food.
At dinner, Mr. Wormwood makes them watch TV, and won't let Matilda defend herself against the idea that she's a cheater.