其它
In December, Tom-the-cat slept for exactly 3 weeks. Which calculations should we do in order to find how many minutes he stayed awake during this month? 
Overseas Competition->Knowledge Point->Calculation Modules->Unit Conversion
The cat slept for exactly 3 weeks for 7 x 3 days.  The cat was awake for 31 - 7 x 3 days.  A day has 24 hours, and an hour has 60 minutes.  Therefore, the cat was awake in (31- 7 x 3) x 24 x 60 