What will be the unit digit of the square of 7992​

4

Step-by-step explanation:

Here you need not completely solve 7992 squared. You can just take the last digit which in this case is 2 and solve for the square of that digit. 2 x 2 = 4. Now if it was a bigger digit which would result in a two digit number when squared you would take the last digit of that number. But, we don't need to do that here since 2 squared is 4.

-35

Step-by-step explanation:

2-3-4=-5

-5-5=-10

-10+5=-5

-5x7=-35