Question

The units place of a number is \[2\] or \[8\], then the last digit of its square is always
A) \[4\]
B) \[6\]
C) \[0\]
D) \[2\]

Answer 1

Hint: From the question we are asked to find the last digit of the square of the number whose units place is \[2\] or \[8\]. For solving this question we will take a few examples whose units place is \[2\] or \[8\] and will find its square and check the last digit and find the required answer to the question. So, our solution will be as follows.

Complete step-by-step solution:
Firstly, as mentioned in the question we will take a number randomly, that is we will take an example whose units place of number is \[2\] or \[8\].
Let us take the number \[22\], here for this number the units place is \[2\].
So, now we will find the square of this number. So, we get,
\[\Rightarrow 22\times 22=484\]
Here we can see that the last digit of the squared number is \[4\].
Let us take another example whose units place will be \[8\].
Let the number be \[18\] where the units place is \[8\].
So, now we will find the square of this number. So, we get,
\[\Rightarrow 18\times 18=324\]
Here we can see that the last digit of the squared number is \[4\].
Therefore, the last digit of its square is always \[4\].

Note: Students should be very careful in doing the calculations. Students should be very careful in taking the examples because the units place must contain either \[2\] or \[8\]. If we take an example where its units place is other than \[2\] or \[8\] then our solution will be wrong.