The number of non-square numbers between 2022 and 2032 is:

2025

The number of non-square numbers between 2022 and 2032 is:

  1. A.

    413

  2. B.

    408

  3. C.

    404

  4. D.

    396

Attempted by 1 students.

Show answer & explanation

Correct answer: C

Concept

For two consecutive perfect squares, n2 and (n + 1)2, every integer that lies strictly between them is automatically a non-square number — no other integer's square can fall strictly between two consecutive perfect squares. Expanding the identity (n + 1)2n2 = 2n + 1 shows that exactly 2n + 1 integers lie in the closed range from n2 + 1 to (n + 1)2 inclusive. One of those integers is the perfect square (n + 1)2 itself, so the count of non-square numbers strictly between n2 and (n + 1)2 is (2n + 1) − 1 = 2n.

Application

Here the two given squares are 2022 and 2032, so n = 202 and n + 1 = 203.

  1. Write the expansion of the difference of the two given squares: (n + 1)2n2 = n2 + 2n + 1 − n2 = 2n + 1.

  2. Substitute n = 202: 20322022 = 2(202) + 1 = 405.

  3. This 405 is the count of integers in the closed range from 2022 + 1 to 2032 inclusive (405 consecutive integers).

  4. Exactly one of those 405 integers, namely 2032 itself, is a perfect square; every other integer in that closed range is strictly between 2022 and 2032 and is therefore non-square (since 2022 and 2032 are consecutive perfect squares, no perfect square can lie strictly in between them).

  5. So the number of non-square integers strictly between 2022 and 2032 is 405 − 1 = 404.

Cross-check

Compute the two squares directly: 2022 = 40804 and 2032 = 41209. The integers strictly between them run from 40805 to 41208, which is 41208 − 40805 + 1 = 404 integers — matching the result obtained from the general identity 2n = 2(202) = 404, and confirming that none of these 404 integers is a perfect square, since the only two perfect squares near this range are the endpoints 2022 and 2032 themselves.

Result

The number of non-square numbers between 2022 and 2032 is 404.

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