Question

Find the sum of the squares of the first 9 natural numbers.

• A. 185
• B. 385
• C. 285
• D. 485

Answer 1

The correct option is C

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

$S_n=1^2+2^2+...+n^2=\frac{n(n+1)(2n+1)}{6}.$

Therefore, the sum of the squares of the first 9 natural numbers is given by

$S_n=1^2+2^2+...+8^2+9^2$

$=\frac{9(9+1)(2\times 9+1)}{6}$

$=\frac{9\times 10\times 19}{6}$

$=285$

Thus, the sum of the squares of the first 9 natural numbers is 285.