NIELIT 2017 OCT Scientific Assistant A - Section A: 16

Question

Count the number of squares in the given figure.

• A. $32$
• B. $30$
• C. $29$
• D. $28$

Answer 1

$\underbrace{4^{2}}_{\text{Size 1 unit}} + \underbrace{3^{2}}_{\text{Size 2 units}}  + \underbrace{2^{2}}_{\text{Size 3 units}}  + \underbrace{1^{2}}_{\text{Size 4 units}}  = 16 + 9 + 4 + 1 = 30$

$\textbf{Note:}\; 1^{2} + 2^{2} + 3^{2} + \dots + n^{2} = \dfrac{n(n+1)(2n+1)}{6}.$

So, the correct answer is $(B).$