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How to add 1 through 100 quickly

What is the sum of 1 to 100?

How to calculate sum 1 to 100?

How to get sum of 1 to any number?

Most popular questions for interview is how to make sum of 1 to 100 or 1 to 50?

So you have to give the answer as well as so fast.

Let we know about the above questions.

Here starting number is 1

Let Ending number is : x

Main formulae is :  n(n+1)/2  If adding 1 to 50 then 50(51)/2=1275

if the ending number is even then 

furmale = 

Examle 1  

 If adding 1 to 1 then

(10x  (10/2))+10/2

(10x5)+5

50+5

55

Example 2

If adding 1 to 50 then

(50 x  (50/2))+50/2

(50x 25)+25

1250+25

1275

So if 1 to 100 then

(100x50)+50

5050

If the ending number is odd then 

formulae =

Example 1

When adding 1 to 11 

11 x (11+1)/2

11x6

66

Example 2

When adding 1 to 51

51 x (51+1)/2

51x 26

1326

So if adding 1 to 99 then

99 x50

4950

Simply We know about How to add 1 to any number. 

Let's do the following

1. add 1 to 35

2. add 1 to 25

3. add 1 to 20

4. add 1 to 40

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