Find the no. of zeros in expression :
1 × 3 × 5 × 7 .......... × 99

Options

A. 24
B. 12
C. 10
D. 0

Answer

To find the number of zeros in the expression \(1 \times 3 \times 5 \times 7 \times \ldots \times 99\), we need to understand how zeros are formed in a product.

### Step-by-Step Solution:

1. **Understanding Zeros in Products**:
- A zero at the end of a number is created by the factors of 10 in that number. A factor of 10 is produced by multiplying 2 and 5 together.

2. **Identifying the Factors in the Given Expression**:
- The expression consists of all odd numbers from 1 to 99. This means we have the numbers: 1, 3, 5, 7, 9, ..., 99.

3. **Counting the Factors of 5**:
- We can identify the multiples of 5 in the sequence of odd numbers. The odd multiples of 5 from 1 to 99 are: 5, 15, 25, 35, 45, 55, 65, 75, 85, 95.
- There are 10 odd multiples of 5.

4. **Counting the Factors of 2**:
- Since all the numbers in the product are odd, there are no even numbers present. Therefore, there are no factors of 2 in the product.

5. **Finding Pairs of Factors**:
- To form a zero, we need at least one pair of (2, 5). Since we have 10 factors of 5 but no factors of 2, we cannot form any pairs.

6. **Conclusion**:
- Since we cannot form any pairs of (2, 5), there will be no zeros at the end of the product.

Thus, the number of zeros in the expression \(1 \times 3 \times 5 \times 7 \times \ldots \times 99\) is **0**.

### Final Answer:
**Number of zeros = 0**