diff --git a/src/bigmath/chain/chain.cpp b/src/bigmath/chain/chain.cpp
index 379a014..cf69f4a 100644
--- a/src/bigmath/chain/chain.cpp
+++ b/src/bigmath/chain/chain.cpp
@@ -230,4 +230,10 @@ namespace bigmath {
         while(shrink()) ;
     }
 
+    // ============================================================================ //
+    //                                 MULTIPLICATION                               //
+    // ============================================================================ //
+
+    chain chain::mul_long(const chain& c) const noexcept {}
+
 }
diff --git a/src/bigmath/chain/chain.hpp b/src/bigmath/chain/chain.hpp
index 28cc5b1..1a6a296 100644
--- a/src/bigmath/chain/chain.hpp
+++ b/src/bigmath/chain/chain.hpp
@@ -61,11 +61,11 @@ namespace bigmath {
 
         void sub(const chain& c) noexcept;
 
-        void mul_long(const chain& c) noexcept;
+        chain mul_long(const chain& c) const noexcept;
 
-        void mul_(const chain& c) noexcept;
+        chain mul_karatsuba(const chain& c) const noexcept;
 
-        void mul_karatsuba(const chain& c) noexcept;
+        chain mul_tomcook3(const chain& c) const noexcept;
 
     public:
 
diff --git a/src/bigmath/numbers/BigFloat.php b/src/bigmath/numbers/BigFloat.php
new file mode 100644
index 0000000..e69de29
diff --git a/src/bigmath/numbers/BigInt.php b/src/bigmath/numbers/BigInt.php
new file mode 100644
index 0000000..e69de29