Irene Posted September 6, 2014 Report Share Posted September 6, 2014 .If seven people meet each other and each shakes hands only once with each other, how many handshakes will there have been? Quote Link to comment Share on other sites More sharing options...
Belatucadrus Posted September 6, 2014 Report Share Posted September 6, 2014 Three thousand five hundred and twenty two point four six. Quote Link to comment Share on other sites More sharing options...
Boris Posted September 6, 2014 Report Share Posted September 6, 2014 Formula is n(n-1)/2, where n = whatever number of people in the group 21 Quote Link to comment Share on other sites More sharing options...
Irene Posted September 6, 2014 Author Report Share Posted September 6, 2014 Formula is n(n-1)/2, where n = whatever number of people in the group 21 In other words: When "a" shakes hands with 'b', 'b' has already shaken hands with 'a' and need not to do it again. Hence the '-1' :D ... good expression with your formula, Boris. ;) Quote Link to comment Share on other sites More sharing options...
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