Question
$ A = \{x \mid x \in \mathbb{N}, x < 5\} $, $ B = \{x \mid x \in \mathbb{Z}, x^2 - 5x + 6 = 0\} $, then the number of onto functions from $ A $ to $ B $ is?
$ A = \{x \mid x \in \mathbb{N}, x < 5\} $, $ B = \{x \mid x \in \mathbb{Z}, x^2 - 5x + 6 = 0\} $, then the number of onto functions from $ A $ to $ B $ is?