Question

what is the sum of the sequence?1+3+5+7...+1001

Answer 1

Let n be no. of terms.
It is an A.P.
a=1,c.d d=3-1=2
l=1001
l=a+(n-1)d
1001=1+(n-1)2
1000/2=n-1
n=500+1=501
\[sn=\frac{ n \left( a+l \right) }{ 2 }=\frac{ 501\left( 1+1001 \right) }{2 }=501*501=?\]
calculate.