Which is not a prime number?

Options

A. 97
B. 1001
C. 127
D. 101

Answer

To determine which number is not a prime number, we need to understand the definition of a prime number. A prime number is a natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers. In other words, a prime number has exactly two distinct positive divisors: 1 and itself.

### Step-by-Step Solution:

1. **Identify the Numbers**: We need to analyze the given numbers to check which one is not a prime number. Let's consider the numbers mentioned: 1001, 127, and 101.

2. **Check 1001**:
- Find the factors of 1001.
- 1001 can be divided by 1, 7, 11, 13, 77, 91, and 143.
- Since 1001 has more than two factors, it is **not a prime number**.

3. **Check 127**:
- Find the factors of 127.
- 127 can only be divided by 1 and 127.
- Since it has exactly two factors, 127 is a **prime number**.

4. **Check 101**:
- Find the factors of 101.
- 101 can only be divided by 1 and 101.
- Since it has exactly two factors, 101 is also a **prime number**.

5. **Conclusion**:
- Among the numbers analyzed, 1001 is the only number that is not a prime number.

### Final Answer:
The number that is not a prime number is **1001**.