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Numbers - General Aptitude

Q1:

(22 + 42 + 62 + ... + 202) = ?

A 770

B 1155

C 1540

D 385 x 385

ANS:C - 1540

(22 + 42 + 62 + ... + 202) = (1 x 2)2 + (2 x 2)2 + (2 x 3)2 + ... + (2 x 10)2 = (22 x 12) + (22 x 22) + (22 x 32) + ... + (22 x 102) = 22 x [12 + 22 + 32 + ... + 102]

Ref: (12 + 22 + 32 + ... + n2) = 1 n(n + 1)(2n + 1)    
6
= 4 x 1 x 10 x 11 x 21
6
= (4 x 5 x 77) = 1540.