diff --git a/include/lexer.hpp b/include/lexer.hpp
index b81d8ec..8efff89 100644
--- a/include/lexer.hpp
+++ b/include/lexer.hpp
@@ -65,12 +65,6 @@ class Lexer {
 
     char peek_next();
 
-    bool is_binary_digit(char);
-
-    bool is_octal_digit(char);
-
-    bool is_underscore(char);
-
     void skip_whitespaces();
 
     void skip_single_line_comment();
@@ -79,6 +73,20 @@ class Lexer {
 
     TokenKind resolve_keyword_token_kind(const char *keyword);
 
+    static bool is_underscore(char);
+
+    static bool is_binary_digit(char);
+
+    static bool is_octal_digit(char);
+
+    static auto hex_to_int(char c) -> int8_t;
+
+    static std::int64_t hex_to_decimal(const std::string&);
+
+    static std::int64_t binary_to_decimal(const std::string&);
+
+    static std::int64_t octal_to_decimal(const std::string&);
+
     /* Operators */
 
     /* Setter & Getter */
diff --git a/src/lexer.cpp b/src/lexer.cpp
index fc38c16..bf42dea 100644
--- a/src/lexer.cpp
+++ b/src/lexer.cpp
@@ -205,21 +205,6 @@ char Lexer::peek_next()
     return '\0';
 }
 
-bool Lexer::is_underscore(char c)
-{
-    return c == '_';
-}
-
-bool Lexer::is_binary_digit(char c)
-{
-    return '1' == c || '0' == c;
-}
-
-bool Lexer::is_octal_digit(char c)
-{
-    return '7' >= c && c >= '0';
-}
-
 void Lexer::skip_whitespaces()
 {
     while (is_source_available()) {
@@ -296,4 +281,46 @@ bool Lexer::is_source_available()
 {
     return current_position < source_code_length;
 }
+
+bool Lexer::is_underscore(char c)
+{
+    return c == '_';
+}
+
+bool Lexer::is_binary_digit(char c)
+{
+    return '1' == c || '0' == c;
+}
+
+bool Lexer::is_octal_digit(char c)
+{
+    return '7' >= c && c >= '0';
+}
+
+std::int64_t Lexer::hex_to_decimal(const std::string &hex)
+{
+    try {
+        return std::stol(hex, nullptr, 16);
+    } catch (...) {
+        return -1;
+    }
+}
+
+std::int64_t Lexer::binary_to_decimal(const std::string &binary)
+{
+    try {
+        return std::stol(binary, nullptr, 2);
+    } catch (...) {
+        return -1;
+    }
+}
+
+std::int64_t Lexer::octal_to_decimal(const std::string &octal)
+{
+    try {
+        return std::stol(octal, nullptr, 8);
+    } catch (...) {
+        return -1;
+    }
+}
 } // namespace jayces