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Question

Which of the following numbers is a perfect square?

The correct answer is
48841

Identifying Perfect Squares Using Number Properties

To determine if a number is a perfect square, we can use two main methods: checking the last digit and calculating the square root.

Last Digit Rule Analysis

Perfect squares have specific last digits. A perfect square cannot end in 2, 3, 7, or 8.

Let's examine the last digit of each option:

  • 48841 ends in 1 (Possible perfect square)
  • 58287 ends in 7 (Cannot be a perfect square)
  • 68763 ends in 3 (Cannot be a perfect square)
  • 38262 ends in 2 (Cannot be a perfect square)

Only 48841 passes this initial check.

Square Root Verification

Now, we verify if 48841 is indeed a perfect square by calculating its square root.

Estimate the square root:

  • We know that $200^2 = 40000$ and $250^2 = 62500$. Therefore, the square root of 48841 lies between 200 and 250.
  • Since 48841 ends in 1, its square root must end in 1 or 9.

Let's test the number 221:

Using LaTeX for calculation:

$ 221^2 = 221 \times 221 $

$ 221 \times 221 = 48841 $

The calculation confirms that $221^2$ equals 48841.

Final Answer

The number 48841 is a perfect square because its square root is an integer (221).

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Important Questions from Number System (Notes)

  1. The sum of the digits of a two-digit number is 10. If 18 is subtracted from it, the digits in the resulting number will be equal. The number is :
  2. A 6-digit number has digits as consecutive natural numbers. The number is always divisible by :
  3. Find the number of trailing zeros in $15620!$
  4. The traffic lights at three different road crossings change after every 48 seconds, 72 seconds and 108 seconds respectively. If they all change simultaneously at 8:20:00 hours, then at what time will they again change simultaneously?
  5. In order to arrange the fractions in any order, if the denominators are made equal, then in which of the following fractions the numerators will be an even number?
    (A) 17/18
    (B) 28/36
    (C) 43/45
    (D) 59/60

    Choose the correct answer from the options given below:
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