diff --git a/modules/13_cpp23/src/mdspan.cpp b/modules/13_cpp23/src/mdspan.cpp
index a236620..e099e17 100644
--- a/modules/13_cpp23/src/mdspan.cpp
+++ b/modules/13_cpp23/src/mdspan.cpp
@@ -2,23 +2,22 @@
 
 namespace cpp23 {
 
-auto make_row_major_matrix(int rows, int cols, int fill) -> std::vector<int> {
-    (void)rows; (void)cols; (void)fill;
-    return {};
+auto make_row_major_matrix(const int rows, const int cols, const int fill) -> std::vector<int> {
+    return std::vector(static_cast<size_t>(rows * cols), fill);
 }
 
-auto matrix_element(
-    std::mdspan<const int, std::extents<int, std::dynamic_extent, std::dynamic_extent>> matrix,
-    int row, int col) -> int {
-    (void)matrix; (void)row; (void)col;
-    return 0;
+auto matrix_element(const std::mdspan<const int, std::extents<int, std::dynamic_extent, std::dynamic_extent>> matrix, const int row, const int col) -> int {
+    return matrix[row, col];
 }
 
-auto row_sums(
-    std::mdspan<const int, std::extents<int, std::dynamic_extent, std::dynamic_extent>> matrix)
-    -> std::vector<int> {
-    (void)matrix;
-    return {};
+auto row_sums(const std::mdspan<const int, std::extents<int, std::dynamic_extent, std::dynamic_extent>> matrix) -> std::vector<int> {
+    auto sums = std::vector<int>(matrix.extent(0));
+    for (auto i = 0; i < matrix.extent(0); ++i) {
+        for (auto j = 0; j < matrix.extent(1); ++j) {
+            sums[i] += matrix[i, j];
+        }
+    }
+    return sums;
 }
 
 }  // namespace cpp23