self Maths Puzzle

It was Elizabeth'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 10 children in the class, how many total handshakes were there?

Read Solution (Total 2)

9+8+7+6+5+4+3+2+1 = 45 handshakes totally.
12 years agoHelpfull: Yes(2) No(0)

there will be 45 hand shakes
soln:: The no. by 1st person will be (n-1)
The no. by 1st person will be (n-2) similar seris will be their::
(n-1=9)+(n-2=8)+(n-3=7)+(n-4=6)+(n-5=5)(n-6=4)+(n-7=3)+(n-8=2)+(n-9=1)+(n-10=0)=45 (answer)
12 years agoHelpfull: Yes(0) No(0)

self Other Question

Can you find a quick and elegant way to add the numbers from 1 to 34 ?

In other words, what is the sum you obtain in the following case:

1 + 2 + 3 + ....... + 34 = "Dad, where had you been?" asked Graham.

"I had been to the attic, my son," replied Dad. "And do you know what I saw there? There was a big web with 15 spiders and flies on it."

"How many spiders were there?" asked the little boy with curiosity.

"Well, there were a total of 100 legs on the web," answered Dad with a smile. "Now you can find out how many spiders were there by yourself. Can't you?"

Can you help the little boy find out how many spiders were on the web in the attic?