Question

Directions (21-25): The following questions are based on
the five three digit numbers given below:
574 658 821 945 247
21. If one is added to the last digit of each of the numbers,
in how many numbers thus formed will the last digit
be a perfect square (1 is also be a perfect square)?
(a) one
(c) three
(e) None of these
(b) Two
(d) four​

Answer 1

(a) one

• A perfect square is a number that can be written as the second exponent of an integer or as the product of an integer by itself. When you multiply an integer by itself, you get a perfect square, which is a positive integer.
• Perfect squares are sums that are the products of integers multiplied by themselves, to put it simply. A perfect square is typically expressed as $x^{2}$, where x is an integer and $x^{2}$'s value is a perfect square.

Here, according to the given information, the numbers are given as,

574, 658, 821, 945, 247.

When 1 is added to the last digits of all the numbers, the numbers are,

575, 659, 822, 946, 248.

Only 659 has 9 as the last digit which is a perfect square.

Hence, option a that is one is correct.

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