It was Helen's first day at school. The teacher suggested that it would be a good idea for each child to meet every other child in the class. The teacher said, "When you meet, please shake hands and introduce yourself by name." If there were 13 children in the class, how many total handshakes were there?

general knowledge math & puzzles

  1. 77

  2. 76

  3. 78

  4. 79

Show answer
Correct Option: C

AI Explanation

To solve this problem, we need to find the total number of handshakes that occur when each child meets every other child in the class.

Let's break down the problem step by step:

Since there are 13 children in the class, let's consider the first child. When the first child meets the other 12 children, they will shake hands with each of them. This results in 12 handshakes.

Similarly, the second child will shake hands with the remaining 11 children, resulting in 11 handshakes.

Following this pattern, the third child will shake hands with the remaining 10 children, resulting in 10 handshakes.

Continuing this process, the fourth child will shake hands with the remaining 9 children, resulting in 9 handshakes.

We can see that the number of handshakes decreases by 1 for each subsequent child.

Summing up all the handshakes, we get:

12 + 11 + 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 = 78

Therefore, the correct answer is option C) 78.

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