diff --git a/modules/12_cpp20/include/concepts.hpp b/modules/12_cpp20/include/concepts.hpp
index 0e834ee..b8b651c 100644
--- a/modules/12_cpp20/include/concepts.hpp
+++ b/modules/12_cpp20/include/concepts.hpp
@@ -3,6 +3,7 @@
 #include <algorithm>
 #include <cctype>
 #include <concepts>
+#include <sstream>
 #include <string>
 #include <vector>
 
@@ -10,14 +11,13 @@ namespace cpp20 {
 
 template <std::integral T>
 [[nodiscard]] auto double_value(T value) -> T {
-    (void)value;
-    return T{};
+    return value * 2;
 }
 
 template <std::floating_point T>
 [[nodiscard]] auto clamp01(T value) -> T {
-    (void)value;
-    return T{};
+    // Converts the 0 and 1 to the right type, which fulfills the std::floating_point concept
+    return std::clamp(value, T{0}, T{1});
 }
 
 template <typename T>
@@ -28,10 +28,17 @@ concept StringLike = requires(T value) {
 
 template <StringLike T>
 [[nodiscard]] auto uppercase_copy(const T& text) -> std::string {
-    (void)text;
-    return {};
+    auto oss = std::ostringstream{};
+    for (auto idx = 0uz; idx < text.size(); idx++) {
+        oss << static_cast<char>(std::toupper(text.data()[idx]));
+    }
+    return oss.str();
 }
 
-[[nodiscard]] auto sum_integral(const std::vector<int>& data) -> int;
+template<typename T>
+requires std::integral<T>
+[[nodiscard]] auto sum_integral(const std::vector<T>& data) -> T {
+    return std::ranges::fold_left(data, T{0}, std::plus{});
+}
 
 }  // namespace cpp20
diff --git a/modules/12_cpp20/src/concepts.cpp b/modules/12_cpp20/src/concepts.cpp
index 6fd74f0..56ff472 100644
--- a/modules/12_cpp20/src/concepts.cpp
+++ b/modules/12_cpp20/src/concepts.cpp
@@ -2,9 +2,5 @@
 
 namespace cpp20 {
 
-auto sum_integral(const std::vector<int>& data) -> int {
-    (void)data;
-    return 0;
-}
 
 }  // namespace cpp20
diff --git a/modules/12_cpp20/test/concepts_test.cpp b/modules/12_cpp20/test/concepts_test.cpp
index 50d56ea..1e65522 100644
--- a/modules/12_cpp20/test/concepts_test.cpp
+++ b/modules/12_cpp20/test/concepts_test.cpp
@@ -15,5 +15,5 @@ TEST(Concepts, UppercaseCopy) {
 }
 
 TEST(Concepts, SumIntegral) {
-    EXPECT_EQ(cpp20::sum_integral({1, 2, 3}), 6);
+    EXPECT_EQ(cpp20::sum_integral<int>({1, 2, 3}), 6);
 }