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The Handshakes

+1 vote
10 people shake hands with each other. How many handshakes have they shook altogether
asked Nov 9, 2013 in Mathematics by anonymous
   

1 Answer

+5 votes
Each person shakes hands with nine other people, so you count 9 handshakes for the first person. But you only count 8 handshakes for the second person because one of his/her handshakes was with the first person and has already been counted. You count seven for the third person because two of her/his handshakes have already been counted. So the total handshakes can be added together

9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 = 45
answered Nov 11, 2013 by stg1.stewart Inquisitive Expert (21,460 points)
Wow i love this puzzle.I did it but with 25.I think the answer was 355 but i forgot.
After reading your comment, I googled for more info and found this problem covered on the web with an additional way to solve it. My answer, 45, is correct. Check out http://mathsbusking.com/shows/handshakes/

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