Question

Without adding, find the sum of the following numbers

1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 =

Answer 1

We know, sum of n odd numbers $=n²$

In the given question, the number of consecutive odd numbers$=9$

So the sum of these numbers$=9²4$

$9\times 9=81$

So the sum of the given numbers$=81$