397 × 397 + 104 × 104 + 2 × 397 × 104 = ?

Correct Answer: 251001
Given expression,
= (397)2 + (104)2 + 2 × 397 × 104
= (397 + 104)2
= (501)2
= (500 + 1)2
= (500)2 + 12 + 2 × 500 × 1
= 250000 + 1 + 1000
= 251001