Question

There are 150 politicians at a meeting.

They each shake hands with everyone
else. How many handshakes were there?

PLEASE HELP ASAP

Answer 1

• 11175

Explanation:

• Person 1 will shake hands with 149 others
• Person 2 ... 148 (excluding the first person)
• Person 2 ... 147 (excluding the first two persons)
• ...
• Person 149 ... 1 (with person 150)
• Person 150 ... none (already had 149 handshakes)

Total handshakes:

• 1 + 2 + ... 149 = 149(1 + 149)/2 = 11175