It’s 21 past 4 (Official clock system).

16:21

It’s 21 past 4.

Correct answer

16:22

It’s 22 past 4.

Error: 1 minute later

16:05

It’s 5 past 4.

Error: read minutes starting from hour markings and adding minutes

16:20

It’s 20 past 4.

Error: confuse hour and minute hands