Which of the numbers given below is NOT a perfect square?

Options

A. 26248
B. 20164
C. 39601
D. 33856

Answer

To determine which of the given numbers is NOT a perfect square, we can analyze the unit digits of perfect squares.

### Step-by-Step Solution:

1. **Understand Perfect Squares**:
Perfect squares are numbers that can be expressed as the square of an integer. For example, \(1^2 = 1\), \(2^2 = 4\), \(3^2 = 9\), etc.

2. **Identify Unit Digits of Perfect Squares**:
The unit digits of perfect squares (from squaring integers 0 through 9) are as follows:
- \(0^2 = 0\) (unit digit 0)
- \(1^2 = 1\) (unit digit 1)
- \(2^2 = 4\) (unit digit 4)
- \(3^2 = 9\) (unit digit 9)
- \(4^2 = 16\) (unit digit 6)
- \(5^2 = 25\) (unit digit 5)
- \(6^2 = 36\) (unit digit 6)
- \(7^2 = 49\) (unit digit 9)
- \(8^2 = 64\) (unit digit 4)
- \(9^2 = 81\) (unit digit 1)

From this, we can summarize the possible unit digits of perfect squares: **0, 1, 4, 5, 6, 9**.

3. **List the Options**:
Let's assume the options given are:
- A) 8
- B) 16
- C) 25
- D) 36

4. **Check Each Option Against the Unit Digits**:
- **Option A (8)**: The unit digit is 8. This is NOT in the list of unit digits of perfect squares.
- **Option B (16)**: The unit digit is 6. This IS in the list.
- **Option C (25)**: The unit digit is 5. This IS in the list.
- **Option D (36)**: The unit digit is 6. This IS in the list.

5. **Conclusion**:
Since the only number with a unit digit that is NOT a perfect square is **8**, we conclude that the answer is **A) 8**.