It’s 18 past 9 (Official clock system).

21:18

It’s 18 past 9.

Correct answer

21:17

It’s 17 past 9.

Error: 1 minute earlier

21:06

It’s 6 past 9.

Error: read minutes starting from hour markings and adding minutes

16:45

It’s a quarter to 5.

Error: confuse hour and minute hands