It is known that the number of handshake within a group of people is the sum of integer between 1 and (number of people in the group - 1). Say there are persons A, B, C, D and E (5 people) in a group and all shook hands, the number of handshakes will be sum of integers between 1 and (5-1) i.e. 1 + 2 + 3 + 4 = 10.
Let's confirm this: - Person A shakes B, C, D, and E (4 handshakes) - Person B shakes C, D, and E (no need to shake A again because A already shook him) (3 handshakes) - Person C shakes D and E (2 handshakes) - Person D shakes E (1 handshake) - Person E don't have to shake anybody, they have all shook him
So, 4 + 3 + 2 + 1 = 10
And also we know that the sum of 1 to n = (n(n+1)) ÷ 2. Say you want to add 1 to 10 that will be = (10 x (10 + 1)) ÷ 2 = (10 x 11) ÷ 2 = 110 ÷ 2 = 55 (also try it with your calculator)
With this information, we now know the number of handshakes in a group of 120 people will be 1 + 2 + 3 + ... + 119
But we don't have to add sequentially like that, we just do (119 x 120) ÷ 2 = 14280 ÷ 2 = 7140
It is known that the number of handshake within a group of people is the sum of integer between 1 and (number of people in the group - 1). Say there are persons A, B, C, D and E (5 people) in a group and all shook hands, the number of handshakes will be sum of integers between 1 and (5-1) i.e. 1 + 2 + 3 + 4 = 10.
Let's confirm this: - Person A shakes B, C, D, and E (4 handshakes) - Person B shakes C, D, and E (no need to shake A again because A already shook him) (3 handshakes) - Person C shakes D and E (2 handshakes) - Person D shakes E (1 handshake) - Person E don't have to shake anybody, they have all shook him
So, 4 + 3 + 2 + 1 = 10
And also we know that the sum of 1 to n = (n(n+1)) ÷ 2. Say you want to add 1 to 10 that will be = (10 x (10 + 1)) ÷ 2 = (10 x 11) ÷ 2 = 110 ÷ 2 = 55 (also try it with your calculator)
With this information, we now know the number of handshakes in a group of 120 people will be 1 + 2 + 3 + ... + 119
But we don't have to add sequentially like that, we just do (119 x 120) ÷ 2 = 14280 ÷ 2 = 7140
Answer: 7140
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Telegram and Signal Havens for Right-Wing Extremists
Since the violent storming of Capitol Hill and subsequent ban of former U.S. President Donald Trump from Facebook and Twitter, the removal of Parler from Amazon’s servers, and the de-platforming of incendiary right-wing content, messaging services Telegram and Signal have seen a deluge of new users. In January alone, Telegram reported 90 million new accounts. Its founder, Pavel Durov, described this as “the largest digital migration in human history.” Signal reportedly doubled its user base to 40 million people and became the most downloaded app in 70 countries. The two services rely on encryption to protect the privacy of user communication, which has made them popular with protesters seeking to conceal their identities against repressive governments in places like Belarus, Hong Kong, and Iran. But the same encryption technology has also made them a favored communication tool for criminals and terrorist groups, including al Qaeda and the Islamic State.
Launched in 2013, Telegram allows users to broadcast messages to a following via “channels”, or create public and private groups that are simple for others to access. Users can also send and receive large data files, including text and zip files, directly via the app.The platform said it has more than 500m active users, and topped 1bn downloads in August, according to data from SensorTower.Riddles Repository Answers from us