Which of the following numbers is not a perfect square ?

Options

A. 1156
B. 4787
C. 2704
D. 3969

Answer

To determine which of the given numbers is not a perfect square, we will analyze the options step by step.

### Step-by-Step Solution:

1. **Understand Perfect Squares**: A perfect square is a number that can be expressed as the square of an integer. For example, \(1^2 = 1\), \(2^2 = 4\), \(3^2 = 9\), etc.

2. **List the Options**: The options given are:
- Option 1: 1, 5, 6
- Option 2: 4, 7, 8
- Option 3: 2, 7, 0, 4
- Option 4: 3, 9, 6, 9

3. **Identify Perfect Squares**:
- **Option 1**:
- 1 is a perfect square (\(1^2\)).
- 5 is not a perfect square.
- 6 is not a perfect square.
- **Option 2**:
- 4 is a perfect square (\(2^2\)).
- 7 is not a perfect square.
- 8 is not a perfect square.
- **Option 3**:
- 2 is not a perfect square.
- 7 is not a perfect square.
- 0 is a perfect square (\(0^2\)).
- 4 is a perfect square (\(2^2\)).
- **Option 4**:
- 3 is not a perfect square.
- 9 is a perfect square (\(3^2\)).
- 6 is not a perfect square.
- 9 is a perfect square (\(3^2\)).

4. **Check the Unit Digits**:
- The unit digits of perfect squares can only be 0, 1, 4, 5, 6, or 9.
- In Option 2, the number 7 appears, which does not match any of the unit digits of perfect squares.

5. **Conclusion**:
- The number 7 in Option 2 is not a perfect square. Thus, the answer is **Option 2: 4, 7, 8**.