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What is the sum of all 3-digit odd positive integers?

 Jul 8, 2020
 #1
avatar+28021 
+1

\(\sum_{50}^{499}\)  2n+1 =247500

 Jul 8, 2020
 #2
avatar+21957 
+1

101 + 103 + 105 + ... + 995 + 997 + 999

 

This is an arithmetic sequence with     t1 = 101     tn = 999     d = 2

 

We can use the formula:  tn  =  t1 + (n - 1)d  to find the number of terms:

--->     999  =  101 + (n - 1)2     --->     n = 450

 

We can use the formula:  Sum  =  n(t1 + tn)/2  to find the sum of the terms:

--->     Sum  =  450(101 + 999)/2     --->     Sum  =  247 500

 Jul 8, 2020
 #3
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-1

hi, how is quarantine? 

 Jul 8, 2020

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