At an academic conference, 20 mathematicians assemble in a seminar room. If each person shakes hands with every other attendee exactly once, how many individual handshakes occur?
190 handshakes
The total combinations of pairs from 20 people is given by 20 choose 2: (20 * 19) / 2 = 190.
About this riddle
Math riddles hide a calculation inside a short story. Pull out the numbers, work out what is being asked, and watch for a trick such as a unit change.
Difficulty: Medium. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
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