diff --git a/maths/sum_of_arithmetic_series.py b/maths/sum_of_arithmetic_series.py
index 3e381b8c2..b320fe477 100644
--- a/maths/sum_of_arithmetic_series.py
+++ b/maths/sum_of_arithmetic_series.py
@@ -1,23 +1,42 @@
-# DarkCoder
-def sum_of_series(first_term: int, common_diff: int, num_of_terms: int) -> float:
+# Reeka
+def sum_of_ap_series(a: int, d: int, n: int) -> int:
     """
-    Find the sum of n terms in an arithmetic progression.
+    Calculates the sum of the first 'n' terms of an arithmetic progression (AP)
+    series with the first term 'a' and common difference 'd'.
 
-    >>> sum_of_series(1, 1, 10)
-    55.0
-    >>> sum_of_series(1, 10, 100)
-    49600.0
+    Parameters:
+    a (int): The first term of the AP.
+    d (int): The common difference between terms.
+    n (int): The number of terms to sum.
+
+    Returns:
+    int: The sum of the first 'n' terms of the AP.
+
+    Examples:
+    >>> sum_of_ap_series(1, 1, 5)  # Sum of first 5 natural numbers
+    15
+    >>> sum_of_ap_series(2, 3, 4)  # Sum of 2, 5, 8, 11
+    26
+    >>> sum_of_ap_series(5, 0, 3)  # Sum of 5, 5, 5
+    15
+    >>> sum_of_ap_series(1, 2, 1)  # Single term AP series
+    1
+    >>> sum_of_ap_series(1, -1, 5)  # Decreasing AP series
+    -5
+    >>> sum_of_ap_series(1, 1, -5)  # Negative 'n' should raise an error
+    Traceback (most recent call last):
+    ...
+    ValueError: Number of terms 'n' must be a positive integer
+    >>> sum_of_ap_series(1, 1, 0)  # Zero terms should also raise an error
+    Traceback (most recent call last):
+    ...
+    ValueError: Number of terms 'n' must be a positive integer
     """
-    total = (num_of_terms / 2) * (2 * first_term + (num_of_terms - 1) * common_diff)
-    # formula for sum of series
-    return total
+    if n <= 0:
+        raise ValueError("Number of terms 'n' must be a positive integer")
+
+    # Formula for the sum of an AP series: S_n = n/2 * (2a + (n-1) * d)
+    return n * (2 * a + (n - 1) * d) // 2
 
 
-def main():
-    print(sum_of_series(1, 1, 10))
-
-
-if __name__ == "__main__":
-    import doctest
-
-    doctest.testmod()
+# Reeka