What could be the possible 'one's'digits of square root of 99856?

Answer 1

When you square a number, the final digit is the final digit of the 'one's' number squared.

Since the only single digit numbers squared which ends in 6 are 4 and 6, the answer is either 4 or 6 (a calculator tells me it is 6)

0 squared is 0. All numbers ending in 0 when squared will end in 0.

1 squared is 1. All numbers ending in 1 when squared will also end in 1.

2 squared is 4. All numbers ending in 2 when squared will end in 4.

3 squared is 9. All numbers ending in 3 when squared will end in 9.

4 squared is 16. All numbers ending in 4 when squared will end in 6.

5 squared is 25. All numbers ending in 5 when squared will end in 5.

6 squared is 36. All numbers ending in 6 when squared will end in 6.

7 squared is 49. All numbers ending in 7 when squared will end in 9.

8 squared is 64. All numbers ending in 8 when squared will end in 4.

9 squared is 81. All numbers ending in 9 when squared will end in 1.

So square numbers can only end with 0, 1, 4, 5, 6 or 9.