+0  
 
+1
103
5
avatar

what is 99+98+97+96 well not just that like adding all numbers less then 100 up that woult take to long to type 

 Apr 20, 2021
 #1
avatar+33572 
+1

100/2 ( 1 + 99)  = 5000

 Apr 20, 2021
 #5
avatar+33572 
+1

My mistake corrected here

 

Sum of the first 99 integers   =====    99/2 ( 1 + 99) = 4950

ElectricPavlov  Apr 20, 2021
 #3
avatar+109 
+1

**EDITED**

 

Never mind I was wrong :/

 Apr 20, 2021
edited by XxMysteriousGirlxX  Apr 20, 2021
 #4
avatar+121002 
+1

Sum of first   n positive integers =  n (n + 1)   /2

 

So...sum  of 1st 100 positive integers =  100  ( 101) /  2   =   50 * 101 =  5050

 

Another way to see this

 

100 + 1  =101

99 + 2  =   101

98 + 3  =  101

.......

 

We will heve 50  paired sums of 101 each  ....so   ...50 * 101  =  5050

 

 

cool cool cool

 Apr 20, 2021

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