It’s 17 past 9 (Official clock system).

21:17

It’s 17 past 9.

Correct answer

21:16

It’s 16 past 9.

Error: 1 minute earlier

21:05

It’s 5 past 9.

Error: read minutes starting from hour markings and adding minutes

15:45

It’s a quarter to 4.

Error: confuse hour and minute hands