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At the annual BrainBashers puzzle discussion conference, 20 people attended.
At the start of the conference, each person shook hands with every other person, how many handshakes took place in total?
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Answer
190.
The first person shook hands with 19 others, the second had already shook hands with the first and therefore shook 18 hands, etc: 19+18+17+16+15+14+13+12+11+10+9+8+7+6+5+4+3+2+1 = 190.
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