Barbara Crane, age 15, of Salt Lake City, Utah, for her question:

Why are there 60 seconds in a minute?

Our number system is based on 10, but the round face of a clock is based on 60. In circles and angles, we use an outmoded number system of 5000 years ago. The ancient Mesopotamians had a number system based on 60, and it was they who chopped the circle into 360 equal degrees. They chose this figure because It divides neatly into sixes and sixties.

We find this ancient 60 theme on the circle of a clock face. There are two sets of six hours on the round dial. There are 60 minutes in each hour and 60 seconds in each minute. We could remodel the circle and chop it into units of 10 to match our modern number system. This would give us a 10 hour dial with 100 minutes in each hour and 100 seconds in each minute. Each second would be one degree Of a circle having 1000 degrees.