Question 11513
I am not sure how much you know about progressions. Consecutive odd numbers come under an Arithmetic progression (a.k.a AP).The difference between consecutive terms is same
for e.g 3-1 = 2
 5-3 = 2 and so on...

Sum of the first n odd numbers is n^2
Sum of first 2 odd numbers = 1+3 = 4
n^2 = 2^2 = 4
So sum of first 100 numbers is 100^2= 10,000