Question

a number becomes a perfect square when we subtract 1 from it. which cant be last digit of that no​

Answer 1

Answer:

3,4,8,9

Step-by-step explanation:

we know that 2,3,7,8 cant be the last digits of a square. in this question the number is 1+perfect square. so the last digits cannot be 3,4,8,9.

#follow

Answer 2

We are given that a number becomes a perfect square when we subtract 1 from it.

We have to find the possible last digit of that number from these 4 choices :-

a) 2

b) 4

c) 5

d) 0

Answer

Option a) 2

Solution

We know that a perfect square ends with the digit 0, 1, 4, 5, 6, and 9. The numbers which end with digit 2, 3, 5 or 7 aren't perfect squares.

So, if the number had a 2 as its last digit, then subtracting 1 would make it a perfect square. So the new number would end with digit 1 which can be a perfect square. Hence, 2 can be the answer.

Now, if it had 4 as its last digit, then subtracting 1 would make it 3, which would make the new number not a perfect square. Hence, 4 can not be the right choice.

If it had 5, subtracting 1 would make it 4, giving chances that the new number can be a perfect square. 5 can also be the answer.

If it has 0, Subtracting 1 would make it 9. It can also be perfect square then. Hence 9 can be the answer too.

But here, 5 and 9 itself can make the number a perfect square. Hence we need not subtract 1 from them. So, the correct answer would be option a) 2