I did it differently to the rest:

2,880,717 = 2400000 + 480000 + 600 + 60 + 57

57 is the only number not divisible by 60 (i.e. one whole hour), so the answer will be 60-57=3 minutes later than than the current minute as you're going back in time.

This only works when the answers are close together like these are.

Who figured this out in approximately 2 minutes?

evansbd wrote:Who figured this out in approximately 2 minutes?

You can do this problem in less than 10 seconds.

Method:

if we have to calculate time 10 minutes before 6:27, it will be 6:17

Similarly,

if 5 minutes, then 6:22
if 15 minutes, then 6:12
if 25 minutes, then 6:02,


Therefore we only have to look at the unit digit to find the answer.

The unit digit is 7, any option with 0 at the end will be the answer.

Hence D.