1/2 + 1/6 + 1/12 + 1/20 + … + 1/90 = ?

$\frac{1}{2} + \frac{1}{6} + \frac{1}{12} + \frac{1}{20} + \dots + \frac{1}{90} = ?$

Show answer & explanation

Correct answer: A

Explanation

$\frac{1}{2} + \frac{1}{6} + \frac{1}{12} + \frac{1}{20} + \dots + \frac{1}{90} = ?$

1/{n(n+1)} = 1/n - 1/(n+1)

= (1 - 1/2) + (1/2 - 1/3) + (1/3 - 1/4) + ... + (1/9 - 1/10)

= 1 - 1/10

= 9/10

SSC GD 2026 PYQ — Question 43