# M May If there are 25 guests, how many handshakes altogether? At a party every guest shakes hands with every other guest once. How many triangles?

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M May If there are 25 guests, how many handshakes altogether? At a party every guest shakes hands with every other guest once. How many triangles?

M May If there are 25 guests, how many handshakes altogether? At a party every guest shakes hands with every other guest once. Each of 25 people shake hands with 24 other people. Two people for each handshake! 25 x 24 2 = 300 shakes 1st2nd3rd……..24th25th 24 +23 +22 +……..1 +0 2423 +2 +…….1 +0 } = 24 x 25 /2/2 = 300 twice +++ 25 twice

M May How many triangles? 16 7 3 1 27

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