diff --git a/src/prime_checker.py b/src/prime_checker.py
new file mode 100644
index 00000000..338fbb00
--- /dev/null
+++ b/src/prime_checker.py
@@ -0,0 +1,35 @@
+def is_prime(n):
+    """
+    Check if a given number is prime.
+    
+    Args:
+        n (int): The number to check for primality.
+    
+    Returns:
+        bool: True if the number is prime, False otherwise.
+    
+    Raises:
+        ValueError: If the input is not a positive integer.
+    """
+    # Check for valid input
+    if not isinstance(n, int):
+        raise ValueError("Input must be an integer")
+    
+    # Handle edge cases
+    if n <= 1:
+        return False
+    
+    # Special case for 2 (the only even prime number)
+    if n == 2:
+        return True
+    
+    # Even numbers greater than 2 are not prime
+    if n % 2 == 0:
+        return False
+    
+    # Check odd divisors up to the square root of n
+    for i in range(3, int(n**0.5) + 1, 2):
+        if n % i == 0:
+            return False
+    
+    return True
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diff --git a/tests/test_prime_checker.py b/tests/test_prime_checker.py
new file mode 100644
index 00000000..430eb5b7
--- /dev/null
+++ b/tests/test_prime_checker.py
@@ -0,0 +1,38 @@
+import pytest
+from src.prime_checker import is_prime
+
+def test_prime_numbers():
+    """Test known prime numbers"""
+    prime_numbers = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29]
+    for num in prime_numbers:
+        assert is_prime(num) is True, f"{num} should be prime"
+
+def test_non_prime_numbers():
+    """Test known non-prime numbers"""
+    non_prime_numbers = [0, 1, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20]
+    for num in non_prime_numbers:
+        assert is_prime(num) is False, f"{num} should not be prime"
+
+def test_large_prime():
+    """Test a larger prime number"""
+    assert is_prime(97) is True
+    assert is_prime(541) is True
+
+def test_large_non_prime():
+    """Test a larger non-prime number"""
+    assert is_prime(100) is False
+    assert is_prime(1000) is False
+
+def test_invalid_input():
+    """Test invalid input types"""
+    with pytest.raises(ValueError):
+        is_prime(3.14)
+    with pytest.raises(ValueError):
+        is_prime("not a number")
+    with pytest.raises(ValueError):
+        is_prime(None)
+
+def test_negative_numbers():
+    """Test negative numbers"""
+    assert is_prime(-7) is False
+    assert is_prime(-2) is False
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