Find the sum of the squares of the first 9 natural numbers.
285
The first 9 natural numbers are 1,2,3,... and 9.
The sum of the squares of the first n natural numbers is given by
Sn=12+22+...+n2=n(n+1)(2n+1)6.
Therefore, the sum of the squares of the first 9 natural numbers is given by
Sn=12+22+...+82+92
=9(9+1)(2×9+1)6
=9×10×196
=285
Thus, the sum of the squares of the first 9 natural numbers is 285.