[anupam2285]

even i cud not understand how u got the solution. plz explain it again.

[genie04]

hello there

plz keep this thread goin ..it is very beneficial for ppl like me who r BAD at QA.

hope to get more tips

arpita

[abhimax]

here is a funda very very important in math and often question based in this come in cat

************************************************** ******************If you want to add all the numbers from F (First) to L (Last), here is an easy way to do it, and many times can be performed in your head.


¢²(F,L)= ( L©÷ - F©÷ + F + L)/2

Where: F is the first number in the number line and L is the Last.

Example:

To add all the numbers from 1 to 10 Plug in 1 for F, and 10 for L.

(10©÷ - 1©÷ + 10 + 1)/2 =
(100 - 1 + 11)/2 =
110/2 = 55

The result is the same as adding all the numbers from 1 to 10 like this:
1+2+3+4+5+6+7+8+9+10=55

This works for all nonnegative integers where 0<F<L. You don't have to start with 1.

************************************************** ********************

cheers
abhi

[cool_simple_boy]

Originally Posted by abhimax @ Wed Sep 29, 2004 1:40 am

here is a funda very very important in math and often question based in this come in cat

************************************************** ******************If you want to add all the numbers from F (First) to L (Last), here is an easy way to do it, and many times can be performed in your head.


¢²(F,L)= ( L©÷ - F©÷ + F + L)/2

Where: F is the first number in the number line and L is the Last.

Example:

To add all the numbers from 1 to 10 Plug in 1 for F, and 10 for L.

(10©÷ - 1©÷ + 10 + 1)/2 =
(100 - 1 + 11)/2 =
110/2 = 55

The result is the same as adding all the numbers from 1 to 10 like this:
1+2+3+4+5+6+7+8+9+10=55

This works for all nonnegative integers where 0<F<L. You don't have to start with 1.

************************************************** ********************

cheers
abhi

Abhi, plz explain this, I am not able to understand this.
Thanks
Rajeev

[MurTuzA]

Originally Posted by abhimax @ Wed Sep 29, 2004 12:10 am

here is a funda very very important in math and often question based in this come in cat

************************************************** ******************If you want to add all the numbers from F (First) to L (Last), here is an easy way to do it, and many times can be performed in your head.


¢²(F,L)= ( L©÷ - F©÷ + F + L)/2

Where: F is the first number in the number line and L is the Last.

Example:

To add all the numbers from 1 to 10 Plug in 1 for F, and 10 for L.

(10©÷ - 1©÷ + 10 + 1)/2 =
(100 - 1 + 11)/2 =
110/2 = 55

The result is the same as adding all the numbers from 1 to 10 like this:
1+2+3+4+5+6+7+8+9+10=55

This works for all nonnegative integers where 0<F<L. You don't have to start with 1.

************************************************** ********************

cheers
abhi

Wow...thats one handy formula.....thanks abhimax

[Asif]

abhi thodi si help aur karde bhai...........


1) (10©÷ - 1©÷ + 10 + 1)/2 =
2) (100 - 1 + 11)/2 =

how it(second bold one) became 100....




---AsIf

[MurTuzA]

Originally Posted by Asif @ Tue Oct 05, 2004 12:27 pm

abhi thodi si help aur karde bhai...........


1) *(10©÷ - 1©÷ + 10 + 1)/2 =
2) *(100 - 1 + 11)/2 =

how it(second bold one) became 100....

---AsIf

The formula is....
The sum of terms from x to y where x and y are non negative intergers and y > x is
(sqr(y) - sqr(x) + x + y )

[zango]

Originally Posted by murtuzaamin_13 @ Tue Oct 05, 2004 3:12 pm

The formula is....
The sum of terms from x to y where x and y are non negative intergers and y > x is
(sqr(y) - sqr(x) + x + y )

And can be derived as the sum of an Arithmetic progression:

b
Sn = Σn = (b - a + 1)(b+a)/2 = (sqr(b) - sqr(a) + b + a) /2
n = a

Where, the common difference d is 1.

It helps to remember the formulae for sum of terms (AP/GP/HP/Squares/Natural numbers/Cubest) etc, coz all other things can be derived therefrom.

Cheers!

[Asif]

hey thnx a lot zango and murtu wid such help from all u pgites its sure my maths wud improve..thnx a ton

---AsIf

[samcool80]

HELLO GUYS
ABHI THAT WAS REALLY A WONDERFUL FORMULA, GO ON ,KEEP IT UP!!!!

NICE ARTICLE TO KEEP THIS THREAD ALIVE

OK I WILL MAKE THE FORMULA VERY CLEAR,ITS LIKE THIS

Sum Of (F TO L) = ( L square - F square + F + L) / 2

F : FIRST NUMBER ON THE NUMBER LINE
L : LAST NUMBER ON THE NUMBER LINE

EG:
SUM OF NO FROM 1 TO 5

SO THE USE OF FORMULA IS

Sum Of (1 TO 5) = ( 5 square - 1 square + 1 + 5) / 2

= ( 25 - 1 + 5 + 1) /2

= 30 / 2

Sum Of (1 TO 5) = 15

I HOPE NOW ALL THE DOUBTS R CLEARED

ALL THE BEST