-  (1399 x 1399) = (1399)2 = (1400 - 1)2 = (1400)2 + 12 - 2 x 1400 x 1
                       = 1960000 + 1 - 2800 = 1960001 - 2800 = 1957201

The multiplication of two numbers 1399 x 1399 can be calculated by applying the distributive law of multiplication. According to the distributive law, when two factors are multiplied, the product of the two factors is equal to the sum of the products of each factor with every term of the other factor.

Mathematically,
1399 x 1399 = (1000 + 300 + 90 + 9) x (1000 + 300 + 90 + 9)
= (1000 x 1000) + (1000 x 300) + (1000 x 90) + (1000 x 9) + (300 x 1000) + (300 x 300) + (300 x 90) + (300 x 9) + (90 x 1000) + (90 x 300) + (90 x 90) + (90 x 9) + (9 x 1000) + (9 x 300) + (9 x 90) + (9 x 9)
= 1000000000 + 3000000 + 90000 + 810 + 3000000 + 90000 + 2700 + 270 + 90000 + 2700 + 8100 + 81 + 810 + 270 + 8100 + 81
= 1957201

Hence, the answer is option D. 1957201

If you think the solution is wrong then please provide your own solution below in the comments section .