Maths Group Learning

Yesterday, we did maths about a math problem which we did in groups. So the topic is about how many hand shakes will everyone get if there's 20 people in a room ( including you ). ( You can't repeat hand shakes ).

How Did We Solve The Problem: 

1  -  At first, we remove 1 from the 20 people because the 1 person is you.

2  -  Then, we make a diagram that shows 19 people above and 1 person ( you ). ( Circles represents person).

3  -  Then, you got to shake everyone hands and that is 19.

4  -  Then, the very first person above is the 2nd person to hand shakes everyone's hand and that will be 18 because he or she already handshake your hand that's why she or he can't shake your hand anymore.

5  -  The 2nd person at the top, will be the 3rd person to shake everyone's hand. He or she can't shake your hand and the 2nd person to try, because they already shakes your hand.

6  -  Keep the same process, until you got zero at the very end of the line.

7  -  Then record all the hand shakes that you have and the hand shakes that they have.

8  -  So it will be like this; 19 + 18 + 17 + 16 + 15 + 14 + 13 + 12 + 11 + 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 = 190

9  -  So the answer is, there are 190 hand shakes at the room