math
posted by bob .
what is the sum of the odd numbers 12009

math 
Reiny
number of terms  n
a=1
term(n) = a + (n1)d
2009 = 1 + (n1)2
2009 = 1 + 2n  2
2n = 2010
n = 1005
sum = (1005/2) (1 + 2009) = 1010025
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