Question

A PS4 uses 8.8 watts when on stand-by mode. How much electricity would be used if you have your PS4 on stand-by 21 hours a day for 2 weeks?

Answer 1

2 weeks = 14 days. 
21 hours × 14 days = 294 hours total.

8.8 watts × 294 hours = 2587.2 Wh or 2.5872 kWh.