diff --git a/src/tools/std20/concepts/test/CMakeLists.txt b/src/tools/std20/concepts/test/CMakeLists.txt
index 326271c..60a6341 100644
--- a/src/tools/std20/concepts/test/CMakeLists.txt
+++ b/src/tools/std20/concepts/test/CMakeLists.txt
@@ -3,6 +3,10 @@ add_cpp_test( std20.concepts.derived_from              derived_from.test.cpp )
 add_cpp_test( std20.concepts.convertible_to            convertible_to.test.cpp )
 add_cpp_test( std20.concepts.common_reference_with     common_reference_with.test.cpp )
 add_cpp_test( std20.concepts.common_with               common_with.test.cpp )
+add_cpp_test( std20.concepts.integral                  integral.test.cpp )
+add_cpp_test( std20.concepts.signed_integral           signed_integral.test.cpp )
+add_cpp_test( std20.concepts.unsigned_integral         unsigned_integral.test.cpp )
+add_cpp_test( std20.concepts.floating_point            floating_point.test.cpp )
 
 add_cpp_test( std20.concepts.equality_comparable       equality_comparable.test.cpp )
 add_cpp_test( std20.concepts.totally_ordered           totally_ordered.test.cpp )
diff --git a/src/tools/std20/concepts/test/floating_point.test.cpp b/src/tools/std20/concepts/test/floating_point.test.cpp
new file mode 100644
index 0000000..29d71d8
--- /dev/null
+++ b/src/tools/std20/concepts/test/floating_point.test.cpp
@@ -0,0 +1,26 @@
+// include Catch2
+#include <catch2/catch_test_macros.hpp>
+
+// what we are testing
+#include "tools/std20/concepts.hpp"
+
+// other includes
+
+// convenience typedefs
+//using namespace njoy::tools;
+namespace std20 = nano::ranges;
+
+SCENARIO( "floating_point" ) {
+
+  CHECK( std20::floating_point< float > );
+  CHECK( std20::floating_point< double > );
+
+  CHECK( ! std20::floating_point< bool > );
+  CHECK( ! std20::floating_point< char > );
+  CHECK( ! std20::floating_point< int > );
+  CHECK( ! std20::floating_point< unsigned int > );
+  CHECK( ! std20::floating_point< std::ptrdiff_t > );
+  CHECK( ! std20::floating_point< std::size_t > );
+  CHECK( ! std20::floating_point< decltype("") > );
+  CHECK( ! std20::floating_point< void > );
+} // SCENARIO
diff --git a/src/tools/std20/concepts/test/integral.test.cpp b/src/tools/std20/concepts/test/integral.test.cpp
new file mode 100644
index 0000000..faa7e36
--- /dev/null
+++ b/src/tools/std20/concepts/test/integral.test.cpp
@@ -0,0 +1,25 @@
+// include Catch2
+#include <catch2/catch_test_macros.hpp>
+
+// what we are testing
+#include "tools/std20/concepts.hpp"
+
+// other includes
+
+// convenience typedefs
+//using namespace njoy::tools;
+namespace std20 = nano::ranges;
+
+SCENARIO( "integral" ) {
+
+  CHECK( std20::integral< bool > );
+  CHECK( std20::integral< char > );
+  CHECK( std20::integral< int > );
+  CHECK( std20::integral< unsigned int > );
+  CHECK( std20::integral< std::ptrdiff_t > );
+  CHECK( std20::integral< std::size_t > );
+
+  CHECK( ! std20::integral< double > );
+  CHECK( ! std20::integral< decltype("") > );
+  CHECK( ! std20::integral< void > );
+} // SCENARIO
diff --git a/src/tools/std20/concepts/test/signed_integral.test.cpp b/src/tools/std20/concepts/test/signed_integral.test.cpp
new file mode 100644
index 0000000..b19aab6
--- /dev/null
+++ b/src/tools/std20/concepts/test/signed_integral.test.cpp
@@ -0,0 +1,24 @@
+// include Catch2
+#include <catch2/catch_test_macros.hpp>
+
+// what we are testing
+#include "tools/std20/concepts.hpp"
+
+// other includes
+
+// convenience typedefs
+//using namespace njoy::tools;
+namespace std20 = nano::ranges;
+
+SCENARIO( "signed_integral" ) {
+
+  CHECK( std20::signed_integral< int > );
+  CHECK( std20::signed_integral< std::ptrdiff_t > );
+
+  CHECK( ! std20::signed_integral< std::size_t > );
+  CHECK( ! std20::signed_integral< bool > );
+  CHECK( ! std20::signed_integral< unsigned int > );
+  CHECK( ! std20::signed_integral< double > );
+  CHECK( ! std20::signed_integral< decltype("") > );
+  CHECK( ! std20::signed_integral< void > );
+} // SCENARIO
diff --git a/src/tools/std20/concepts/test/unsigned_integral.test.cpp b/src/tools/std20/concepts/test/unsigned_integral.test.cpp
new file mode 100644
index 0000000..71d6066
--- /dev/null
+++ b/src/tools/std20/concepts/test/unsigned_integral.test.cpp
@@ -0,0 +1,25 @@
+// include Catch2
+#include <catch2/catch_test_macros.hpp>
+
+// what we are testing
+#include "tools/std20/concepts.hpp"
+
+// other includes
+
+// convenience typedefs
+//using namespace njoy::tools;
+namespace std20 = nano::ranges;
+
+SCENARIO( "unsigned_integral" ) {
+
+  CHECK( std20::unsigned_integral< bool > );
+  CHECK( std20::unsigned_integral< unsigned int > );
+  CHECK( std20::unsigned_integral< std::size_t > );
+
+  CHECK( ! std20::unsigned_integral< std::ptrdiff_t > );
+  CHECK( ! std20::unsigned_integral< char > );
+  CHECK( ! std20::unsigned_integral< int > );
+  CHECK( ! std20::unsigned_integral< double > );
+  CHECK( ! std20::unsigned_integral< decltype("") > );
+  CHECK( ! std20::unsigned_integral< void > );
+} // SCENARIO