1.  397 x 397 + 104 x 104 + 2 x 397 x 104 = ?
A. 250001
B. 251001
C. 260101
D. 261001

Answer: Option B

Explanation:

Given Exp. = (397)2 + (104)2 + 2 x 397 x 104
= (397 + 104)2
= (501)2 = (500 + 1)2
= (5002) + (1)2 + (2 x 500 x 1)
= 250000 + 1 + 1000
= 251001