May 2013

Let's shake hands


The class of '80 was having a reunion and I was excited at the prospect of meeting my friends with whom I had played as a child.

Those were happy days and we had played together, quarreled, fought, made up, teased, helped, played tricks, got scolded by teachers, and what not! And, then, we had gone our ways. Few of us did meet occasionally but never since passing out had all of us met together again.

The hall was resounding with laughter and back-slapping. When all of us had gathered, there was formal round of handshakes. Everyone shook hands with everyone else.

I was so carried away that I counted the number of handshakes. There were 1225 handshakes in all!

Everyone shook hands with everyone else in the hall exactly once and there were 1225 handshakes.

Can you tell how many of us were present in the hall?

Click here for the solution

Some useful links for
your career:

  • Union Public Service Commission -
  • IIT-Kharagpur -
  • Indian Statistical Institute -
  • Indian Institute of Technology Madras -
  • Indian Institute of Management, Ahmedabad -
  • Indian Institute of Mass Commission -
  • IIT Bombay -
  • Indian School of Mines, Dhanbad -
  • Birla Institute of Technology, Ranchi -
  • Central Institute of Fisheries Nautical and Engineering Training -
  • Indian Institute of Information Technology, Allahabad (Deemed University) -
  • Central Marine Fisheries Research Institute, Kochi -
  • Tata Institute of Social Sciences, Mumbai -

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