Total newbie question

[trip7]

Could someone show me how to add the numbers 1 thru 50 and display the total of 1275 the easy way. My brain wont close in on this one and I dont want to use a ton of variables.

Thanks in advance
trip7

[limey_pilot]

you mean something like this?


long count = 0;

for( long i = 0; i <= 50; i++)
count += i;

[Joseph_R_Thomas]

int result = 0;
for(int i = 0 ; i < 51 ; i ++ )
{
	result += i ;
}

thats it...
'result' is 1275

[souldog]

sum = (50*51)/2= 25*51

[trip7]

Exactly what I was looking for and thanks for your help all!

[souldog]

P.S.

in general the sum of the numbers from 1 to n is

sum = n*(n+1)/2

and in general to sum the numbers from m to n with 1 <= m < n

sum = (m+n)(m-n+1)/2

proof

write the sum in two ways

sum = m + (m+1) + (m+2) +...+ (n-2) + (n-1) + n
sum = n + (n - 1) + (n - 2)+...+ (m+2) + (m+1) + m

Now add the columns

2*sum = (m+n)+(m+n)+(m+n)+...+(m+n)+(m+n)+(m+n)

How many terms are on the right? (m-n+1)

so
2*sum = (m+n)(m-n+1)

and it done

[Joseph_R_Thomas]

Originally posted by souldog
sum = (50*51)/2= 25*51

well i alwasys thought...there is a vast difference between experience+coolness and education...

cool Mr.Souldog....expected a cool answer from you like above..




now comes the formula.....cool!!!!

[limey_pilot]

Of course, there is always a good way and an excellent way of doing something