Because, madam, he is basically incapable of understanding the problem.
7 seconds sound clip from the Mr. Topaze (1961) movie soundboard.
You can hear this line at 00:37:11 in the Blu-ray version of the movie.
Quote context
[...]
- Here he had another nought yesterday for mathematics.
- There's no doubt about it-the last in the class is Pitard Verniard.
- And why is my grandson bottom of the class?
- Because he keeps getting noughts.
- But why does he keep getting noughts?
- Because, madam, he is basically incapable of understanding the problem.
- And why is he basically incapable of understanding the problem?
- My grandson does not understand the problem because the whole thing is pre-arranged.
[...]