diff --git a/maths/area.py b/maths/area.py
index 3a0fd9739..0cbfd7957 100644
--- a/maths/area.py
+++ b/maths/area.py
@@ -12,7 +12,13 @@ def surface_area_cube(side_length: float) -> float:
     6
     >>> surface_area_cube(3)
     54
+    >>> surface_area_cube(-1)
+    Traceback (most recent call last):
+        ...
+    ValueError: surface_area_cube() only accepts non-negative values
     """
+    if side_length < 0:
+        raise ValueError("surface_area_cube() only accepts non-negative values")
     return 6 * side_length ** 2
 
 
@@ -26,7 +32,13 @@ def surface_area_sphere(radius: float) -> float:
     314.1592653589793
     >>> surface_area_sphere(1)
     12.566370614359172
+    >>> surface_area_sphere(-1)
+    Traceback (most recent call last):
+        ...
+    ValueError: surface_area_sphere() only accepts non-negative values
     """
+    if radius < 0:
+        raise ValueError("surface_area_sphere() only accepts non-negative values")
     return 4 * pi * radius ** 2
 
 
@@ -34,9 +46,23 @@ def area_rectangle(length: float, width: float) -> float:
     """
     Calculate the area of a rectangle
 
-    >>> area_rectangle(10,20)
+    >>> area_rectangle(10, 20)
     200
+    >>> area_rectangle(-1, -2)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_rectangle() only accepts non-negative values
+    >>> area_rectangle(1, -2)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_rectangle() only accepts non-negative values
+    >>> area_rectangle(-1, 2)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_rectangle() only accepts non-negative values
     """
+    if length < 0 or width < 0:
+        raise ValueError("area_rectangle() only accepts non-negative values")
     return length * width
 
 
@@ -46,7 +72,13 @@ def area_square(side_length: float) -> float:
 
     >>> area_square(10)
     100
+    >>> area_square(-1)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_square() only accepts non-negative values
     """
+    if side_length < 0:
+        raise ValueError("area_square() only accepts non-negative values")
     return side_length ** 2
 
 
@@ -54,9 +86,23 @@ def area_triangle(base: float, height: float) -> float:
     """
     Calculate the area of a triangle
 
-    >>> area_triangle(10,10)
+    >>> area_triangle(10, 10)
     50.0
+    >>> area_triangle(-1, -2)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_triangle() only accepts non-negative values
+    >>> area_triangle(1, -2)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_triangle() only accepts non-negative values
+    >>> area_triangle(-1, 2)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_triangle() only accepts non-negative values
     """
+    if base < 0 or height < 0:
+        raise ValueError("area_triangle() only accepts non-negative values")
     return (base * height) / 2
 
 
@@ -64,9 +110,23 @@ def area_parallelogram(base: float, height: float) -> float:
     """
     Calculate the area of a parallelogram
 
-    >>> area_parallelogram(10,20)
+    >>> area_parallelogram(10, 20)
     200
+    >>> area_parallelogram(-1, -2)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_parallelogram() only accepts non-negative values
+    >>> area_parallelogram(1, -2)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_parallelogram() only accepts non-negative values
+    >>> area_parallelogram(-1, 2)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_parallelogram() only accepts non-negative values
     """
+    if base < 0 or height < 0:
+        raise ValueError("area_parallelogram() only accepts non-negative values")
     return base * height
 
 
@@ -74,9 +134,39 @@ def area_trapezium(base1: float, base2: float, height: float) -> float:
     """
     Calculate the area of a trapezium
 
-    >>> area_trapezium(10,20,30)
+    >>> area_trapezium(10, 20, 30)
     450.0
+    >>> area_trapezium(-1, -2, -3)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_trapezium() only accepts non-negative values
+    >>> area_trapezium(-1, 2, 3)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_trapezium() only accepts non-negative values
+    >>> area_trapezium(1, -2, 3)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_trapezium() only accepts non-negative values
+    >>> area_trapezium(1, 2, -3)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_trapezium() only accepts non-negative values
+    >>> area_trapezium(-1, -2, 3)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_trapezium() only accepts non-negative values
+    >>> area_trapezium(1, -2, -3)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_trapezium() only accepts non-negative values
+    >>> area_trapezium(-1, 2, -3)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_trapezium() only accepts non-negative values
     """
+    if base1 < 0 or base2 < 0 or height < 0:
+        raise ValueError("area_trapezium() only accepts non-negative values")
     return 1 / 2 * (base1 + base2) * height
 
 
@@ -86,7 +176,13 @@ def area_circle(radius: float) -> float:
 
     >>> area_circle(20)
     1256.6370614359173
+    >>> area_circle(-1)
+    Traceback (most recent call last):
+        ...
+    ValueError: area_circle() only accepts non-negative values
     """
+    if radius < 0:
+        raise ValueError("area_circle() only accepts non-negative values")
     return pi * radius ** 2