Question

find the sum of odd integers from 1 to 2001

Answer 1

This sequece is in the form of A.P
Common difference=2 first term is 1
a+(n-1)d=2001
so
solve this we get n=1001

sn=n/2(2a+n-1)d
substive values we get
1001*1001
1002001 is the answer

Answer 2

the formation sequence will be this:
so,
⇒1001*1001
⇒1002001