EASY one for your kids!

The two hands on a clock are exactly at right-angles, when will that next occur?

32 minutes and 44 seconds later.

Originally posted by Sebastian Yap
32 minutes and 44 seconds later.

Every hour, the minute hand goes 360 degrees and the hour hand 30 degrees, so X hours = minute hand gains 330 times X degrees. To gain exactly 180 degrees that's 180 / 330 hrs, or 60 x 180 / 330 minutes. That is, 32 minutes and 43 7/11 seconds.. doesn't even depends on whether you start at the hands at the 3 o'clock or the 9 o'clock position.