89^2= ____

89-2-a-90-1-2-b-90-2-c-1-2-d-9-2-the-question-was

89^2= ____
A. (90-1)^2
B. 90^2
C. 1^2
D. 9^2
The correct option is A. (90-1)^2

If we have to find the square of the number which is near 0 we use the second variation i.e. (90-1)^2. This would help us and make the calculations easier.
Therefore (90-1)^2= 90^2-2×90×1+1^2
Therefore (90-1)^2= 8100-180+1
Therefore (90-1)^2=7921.