------
## 最终结论
```python
def count_Primes_nums(n):
    if n < 2:
        return 0
    count = 0
    for num in range(2, n):
        is_prime = True
        for i in range(2, int(num**0.5) + 1):
            if num % i == 0:
                is_prime = False
                break
        if is_prime:
            count += 1
    return count

# Test cases
assert count_Primes_nums(5) == 2
assert count_Primes_nums(10) == 4
assert count_Primes_nums(100) == 25
```