Think it over

This section ofResonance is meant to raise thought-provoking, interesting, or just plain brain-teasing questions every month, and discuss answers a few months later. Readers are welcome to send in suggestions for such questions, solutions to questions already posed, comments on the solutions discussed in the journal, etc. toResonance Indian Academy of Sciences, Bangalore 560 080, with “Think It Over” written on the cover or card to help us sort the correspondence. Due to limitations of space, it may not be possible to use all the material received. However, the coordinators of this section (currently C S Yogananda and R Nityananda) will try and select items which best illustrate various ideas and concepts, for inclusion in this section.