diff --git a/DIRECTORY.md b/DIRECTORY.md
index 2399b894ef5..e9d51a2df60 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -171,6 +171,7 @@
   * [Vector Ops](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/machine_learning/vector_ops.hpp)
 
 ## Math
+  * [Approximate Pi](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/math/approximate_pi.cpp)
   * [Area](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/math/area.cpp)
   * [Armstrong Number](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/math/armstrong_number.cpp)
   * [Binary Exponent](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/math/binary_exponent.cpp)
@@ -211,6 +212,7 @@
   * [N Choose R](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/math/n_choose_r.cpp)
   * [Ncr Modulo P](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/math/ncr_modulo_p.cpp)
   * [Number Of Positive Divisors](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/math/number_of_positive_divisors.cpp)
+  * [Perimeter](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/math/perimeter.cpp)
   * [Power For Huge Numbers](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/math/power_for_huge_numbers.cpp)
   * [Power Of Two](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/math/power_of_two.cpp)
   * [Prime Factorization](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/math/prime_factorization.cpp)
diff --git a/math/perimeter.cpp b/math/perimeter.cpp
new file mode 100644
index 00000000000..c91ded67a2e
--- /dev/null
+++ b/math/perimeter.cpp
@@ -0,0 +1,287 @@
+/**
+ * @file
+ * @brief Implementations for the
+ * [perimeter](https://en.wikipedia.org/wiki/Perimeter) of various shapes
+ * @details The  of a shape is the amount of 2D space it takes up.
+ * All shapes have a formula for their perimeter.
+ * These implementations support multiple return types.
+ *
+ * @author [OGscorpion](https://github.com/OGscorpion)
+ */
+#define _USE_MATH_DEFINES
+#include <cassert>   /// for assert
+#include <cmath>     /// for M_PI definition and pow()
+#include <cstdint>   /// for uint16_t datatype
+#include <iostream>  /// for IO operations
+
+/**
+ * @namespace math
+ * @brief Mathematical algorithms
+ */
+namespace math {
+/**
+ * @brief perimeter of a [square](https://en.wikipedia.org/wiki/Square) (4 * l)
+ * @param length is the length of the square
+ * @returns perimeter of square
+ */
+template <typename T>
+T square_perimeter(T length) {
+    return 4 * length;
+}
+
+/**
+ * @brief perimeter of a [rectangle](https://en.wikipedia.org/wiki/Rectangle) (
+ * 2(l + w) )
+ * @param length is the length of the rectangle
+ * @param width is the width of the rectangle
+ * @returns perimeter of the rectangle
+ */
+template <typename T>
+T rect_perimeter(T length, T width) {
+    return 2 * (length + width);
+}
+
+/**
+ * @brief perimeter of a [triangle](https://en.wikipedia.org/wiki/Triangle) (a +
+ * b + c)
+ * @param base is the length of the bottom side of the triangle
+ * @param height is the length of the tallest point in the triangle
+ * @returns perimeter of the triangle
+ */
+template <typename T>
+T triangle_perimeter(T base, T height, T hypotenuse) {
+    return base + height + hypotenuse;
+}
+
+/**
+ * @brief perimeter of a
+ * [circle](https://en.wikipedia.org/wiki/perimeter_of_a_circle) (2 * pi * r)
+ * @param radius is the radius of the circle
+ * @returns perimeter of the circle
+ */
+template <typename T>
+T circle_perimeter(T radius) {
+    return 2 * M_PI * radius;
+}
+
+/**
+ * @brief perimeter of a
+ * [parallelogram](https://en.wikipedia.org/wiki/Parallelogram) 2(b + h)
+ * @param base is the length of the bottom side of the parallelogram
+ * @param height is the length of the tallest point in the parallelogram
+ * @returns perimeter of the parallelogram
+ */
+template <typename T>
+T parallelogram_perimeter(T base, T height) {
+    return 2 * (base + height);
+}
+
+/**
+ * @brief surface perimeter of a [cube](https://en.wikipedia.org/wiki/Cube) ( 12
+ * * l)
+ * @param length is the length of the cube
+ * @returns surface perimeter of the cube
+ */
+template <typename T>
+T cube_surface_perimeter(T length) {
+    return 12 * length;
+}
+
+/**
+ * @brief surface perimeter of a
+ * [n-polygon](https://www.cuemath.com/measurement/perimeter-of-polygon/) ( n *
+ * l)
+ * @param length is the length of the polygon
+ * @param sides is the number of sides of the polygon
+ * @returns surface perimeter of the polygon
+ */
+template <typename T>
+T n_polygon_surface_perimeter(T sides, T length) {
+    return sides * length;
+}
+
+/**
+ * @brief surface perimeter of a
+ * [cylinder](https://en.wikipedia.org/wiki/Cylinder) (2 * radius + 2 * height)
+ * @param radius is the radius of the cylinder
+ * @param height is the height of the cylinder
+ * @returns surface perimeter of the cylinder
+ */
+template <typename T>
+T cylinder_surface_perimeter(T radius, T height) {
+    return (2 * radius) + (2 * height);
+}
+}  // namespace math
+
+/**
+ * @brief Self-test implementations
+ * @returns void
+ */
+static void test() {
+    // I/O variables for testing
+    uint16_t int_length = 0;      // 16 bit integer length input
+    uint16_t int_width = 0;       // 16 bit integer width input
+    uint16_t int_base = 0;        // 16 bit integer base input
+    uint16_t int_height = 0;      // 16 bit integer height input
+    uint16_t int_hypotenuse = 0;  // 16 bit integer hypotenuse input
+    uint16_t int_sides = 0;       // 16 bit integer sides input
+    uint16_t int_expected = 0;    // 16 bit integer expected output
+    uint16_t int_perimeter = 0;   // 16 bit integer output
+
+    float float_length = NAN;     // float length input
+    float float_expected = NAN;   // float expected output
+    float float_perimeter = NAN;  // float output
+
+    double double_length = NAN;     // double length input
+    double double_width = NAN;      // double width input
+    double double_radius = NAN;     // double radius input
+    double double_height = NAN;     // double height input
+    double double_expected = NAN;   // double expected output
+    double double_perimeter = NAN;  // double output
+
+    // 1st test
+    int_length = 5;
+    int_expected = 20;
+    int_perimeter = math::square_perimeter(int_length);
+
+    std::cout << "perimeter OF A SQUARE (int)" << std::endl;
+    std::cout << "Input Length: " << int_length << std::endl;
+    std::cout << "Expected Output: " << int_expected << std::endl;
+    std::cout << "Output: " << int_perimeter << std::endl;
+    assert(int_perimeter == int_expected);
+    std::cout << "TEST PASSED" << std::endl << std::endl;
+
+    // 2nd test
+    float_length = 2.5;
+    float_expected = 10;
+    float_perimeter = math::square_perimeter(float_length);
+
+    std::cout << "perimeter OF A SQUARE (float)" << std::endl;
+    std::cout << "Input Length: " << float_length << std::endl;
+    std::cout << "Expected Output: " << float_expected << std::endl;
+    std::cout << "Output: " << float_perimeter << std::endl;
+    assert(float_perimeter == float_expected);
+    std::cout << "TEST PASSED" << std::endl << std::endl;
+
+    // 3rd test
+    int_length = 4;
+    int_width = 7;
+    int_expected = 22;
+    int_perimeter = math::rect_perimeter(int_length, int_width);
+
+    std::cout << "perimeter OF A RECTANGLE (int)" << std::endl;
+    std::cout << "Input Length: " << int_length << std::endl;
+    std::cout << "Input Width: " << int_width << std::endl;
+    std::cout << "Expected Output: " << int_expected << std::endl;
+    std::cout << "Output: " << int_perimeter << std::endl;
+    assert(int_perimeter == int_expected);
+    std::cout << "TEST PASSED" << std::endl << std::endl;
+
+    // 4th test
+    double_length = 2.5;
+    double_width = 5.7;
+    double_expected = 16.4;
+    double_perimeter = math::rect_perimeter(double_length, double_width);
+
+    std::cout << "perimeter OF A RECTANGLE (double)" << std::endl;
+    std::cout << "Input Length: " << double_length << std::endl;
+    std::cout << "Input Width: " << double_width << std::endl;
+    std::cout << "Expected Output: " << double_expected << std::endl;
+    std::cout << "Output: " << double_perimeter << std::endl;
+    assert(double_perimeter == double_expected);
+    std::cout << "TEST PASSED" << std::endl << std::endl;
+
+    // 5th test
+    int_base = 10;
+    int_height = 3;
+    int_hypotenuse = 5;
+    int_expected = 18;
+    int_perimeter =
+        math::triangle_perimeter(int_base, int_height, int_hypotenuse);
+
+    std::cout << "perimeter OF A TRIANGLE" << std::endl;
+    std::cout << "Input Base: " << int_base << std::endl;
+    std::cout << "Input Height: " << int_height << std::endl;
+    std::cout << "Expected Output: " << int_expected << std::endl;
+    std::cout << "Output: " << int_perimeter << std::endl;
+    assert(int_perimeter == int_expected);
+    std::cout << "TEST PASSED" << std::endl << std::endl;
+
+    // 6th test
+    double_radius = 6;
+    double_expected =
+        37.69911184307752;  // rounded down because the double datatype
+                            // truncates after 14 decimal places
+    double_perimeter = math::circle_perimeter(double_radius);
+
+    std::cout << "perimeter OF A CIRCLE" << std::endl;
+    std::cout << "Input Radius: " << double_radius << std::endl;
+    std::cout << "Expected Output: " << double_expected << std::endl;
+    std::cout << "Output: " << double_perimeter << std::endl;
+    assert(double_perimeter == double_expected);
+    std::cout << "TEST PASSED" << std::endl << std::endl;
+
+    // 7th test
+    int_base = 6;
+    int_height = 7;
+    int_expected = 26;
+    int_perimeter = math::parallelogram_perimeter(int_base, int_height);
+
+    std::cout << "perimeter OF A PARALLELOGRAM" << std::endl;
+    std::cout << "Input Base: " << int_base << std::endl;
+    std::cout << "Input Height: " << int_height << std::endl;
+    std::cout << "Expected Output: " << int_expected << std::endl;
+    std::cout << "Output: " << int_perimeter << std::endl;
+    assert(int_perimeter == int_expected);
+    std::cout << "TEST PASSED" << std::endl << std::endl;
+
+    // 8th test
+    double_length = 5.5;
+    double_expected = 66.0;
+    double_perimeter = math::cube_surface_perimeter(double_length);
+
+    std::cout << "SURFACE perimeter OF A CUBE" << std::endl;
+    std::cout << "Input Length: " << double_length << std::endl;
+    std::cout << "Expected Output: " << double_expected << std::endl;
+    std::cout << "Output: " << double_perimeter << std::endl;
+    assert(double_perimeter == double_expected);
+    std::cout << "TEST PASSED" << std::endl << std::endl;
+
+    // 9th test
+    int_sides = 7;
+    int_length = 10;
+    int_expected = 70;
+    int_perimeter = math::n_polygon_surface_perimeter(int_sides, int_length);
+
+    std::cout << "SURFACE perimeter OF A N-POLYGON" << std::endl;
+    std::cout << "Input Sides: " << int_sides << std::endl;
+    std::cout << "Input Length: " << int_length << std::endl;
+    std::cout << "Expected Output: " << int_expected << std::endl;
+    std::cout << "Output: " << int_perimeter << std::endl;
+    assert(int_perimeter == int_expected);
+    std::cout << "TEST PASSED" << std::endl << std::endl;
+
+    // 10th test
+    double_radius = 4.0;
+    double_height = 7.0;
+    double_expected = 22.0;
+    double_perimeter =
+        math::cylinder_surface_perimeter(double_radius, double_height);
+
+    std::cout << "SURFACE perimeter OF A CYLINDER" << std::endl;
+    std::cout << "Input Radius: " << double_radius << std::endl;
+    std::cout << "Input Height: " << double_height << std::endl;
+    std::cout << "Expected Output: " << double_expected << std::endl;
+    std::cout << "Output: " << double_perimeter << std::endl;
+    assert(double_perimeter == double_expected);
+    std::cout << "TEST PASSED" << std::endl << std::endl;
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main() {
+    test();  // run self-test implementations
+    return 0;
+}