Ok, I give up - middle school math. . .

[episodic]

Find a novel way to add all of the integers between 1 and 100

Method must not include a calculator - nor may it include 1+2+3 - figuring it out the old fashioned way.


It must be understood and explainable by a 6th grader. . .


sigh. . .

 

[Shawn]

I used to know how to do this, but I have long since forgotten. 😛

 

[George P Burdell]

n (n + 1) /2 (if i remember correctly)

edit: where n = 100

 

[fallenangel99]

k(2n+k-1) / 2
k = count of integers
n = starting number

(the formula is for consecutive integers)
k = 100-1 = 99+1 = 100 integers
n =1

Plug the numbers in and you get your answer.

I know this formula because I am taking my GMAT exam tomm. 🙂 🙂

 

[Gibson486]

they learn about series in the 6th grade now??? is this in China?

 

[TecHNooB]

1 + 100 = 101
2 + 99 = 101
3 + 98 = 101
4 + 97 = 101

Start with that~

 

[Alone]

Fvck that I still don't know this ******.

 

[Savij]

1+99 = 100
2+98=100
.
.
.
49+51=100
+50
+100


is the same as 49*100+150

 

[episodic]

Thanks - found another one too googling around - add 1st and last number 1+100 = 101 - ask yourself how many 'pairs' are between the 2 numbers (100/2) - there are 50 pairs - multiply that times 101 = 5050. . .


The other ways are cool too

Not china - rural south. . ., hard teacher.

 

[thesurge]

By induction,

n=1
(1)(1+1)/2=1=1

n=n+1
n(n+1)/2+n+1=(n+1)((n+1)+1)/2

See:
1+100=101
2+99=101
...
50 pairs of 101=...

 

[SoLiDus88]

look up gauss...

 

[ungsunghero]

Originally posted by: episodic
Thanks - found another one too googling around - add 1st and last number 1+100 = 101 - ask yourself how many 'pairs' are between the 2 numbers (100/2) - there are 50 pairs - multiply that times 101 = 5050. . .


The other ways are cool too

Not china - rural south. . ., hard teacher.

That's how I learned it back in elementary school.

 

[Gibson486]

Originally posted by: episodic
Thanks - found another one too googling around - add 1st and last number 1+100 = 101 - ask yourself how many 'pairs' are between the 2 numbers (100/2) - there are 50 pairs - multiply that times 101 = 5050. . .


The other ways are cool too

Not china - rural south. . ., hard teacher.

Atleast we have some hope in our school system....although, I must admit I am surpised that this is in the south.

 

[ed21x]

Originally posted by: Gibson486

Originally posted by: episodic
Thanks - found another one too googling around - add 1st and last number 1+100 = 101 - ask yourself how many 'pairs' are between the 2 numbers (100/2) - there are 50 pairs - multiply that times 101 = 5050. . .


The other ways are cool too

Not china - rural south. . ., hard teacher.

Atleast we have some hope in our school system....although, I must admit I am surpised that this is in the south.

the south certainly does better in schooling than such backwards school systems in california that somehow manages to be ranked below 47th every year.

 

[SsupernovaE]

I went to high school in the South. Richmond, VA. Although, it was one of the best public schools in the country.

 

[HaxorNubcake]

Gauss figured it out himself in primary school. wtf is wrong with you?! :|