Question

What will be the unit digit of a square of the given number 297?
A.9
B.7
C.3
D.1

Answer 1

Hint: Squaring a number or finding the square is nothing but multiplying the same number with itself. Sp when we multiply a number with itself the unit digit of the number gives us the idea of the unit digit of the square also.

Complete step by step solution:
We know that the square of a number is nothing but the process of multiplication.
In finding the square of a number the units place digits are sequentially 1,4,9,6,5,6,9,4,1.
These are the unit place digits of squares of a single number like 1,2,3,4,5,6,7,8,9 respectively.
Now the units place number will not change since units place digits will be any number from these only. So these numbers will directly give the number on the unit's place.
So 297 is the number given. So on squaring the units place digit will be units place digit of square of 7.
As we know on squaring 7 we get 49 as the answer and the unit's place has 9.
 So on squaring above number units the place digit will be 9.
So option A is the correct option.
So, the correct answer is “Option A”.

Note: Note that this can be done for units place digit directly but not for other place values. Thus we have to calculate the square directly in other cases. Also note that the square of any number with zero in units place will result in zero in units place of the answer.