diff --git a/lettucedetect/detectors/factory.py b/lettucedetect/detectors/factory.py
index 430e616..2b27434 100644
--- a/lettucedetect/detectors/factory.py
+++ b/lettucedetect/detectors/factory.py
@@ -23,5 +23,9 @@ def make_detector(method: str, **kwargs) -> BaseDetector:
         from lettucedetect.detectors.llm import LLMDetector
 
         return LLMDetector(**kwargs)
+    elif method == "number":
+        from lettucedetect.detectors.number import NumberDetector
+
+        return NumberDetector()
     else:
         raise ValueError(f"Unknown detector method: {method}. Use one of: transformer, llm")
diff --git a/lettucedetect/detectors/number.py b/lettucedetect/detectors/number.py
new file mode 100644
index 0000000..d261c00
--- /dev/null
+++ b/lettucedetect/detectors/number.py
@@ -0,0 +1,84 @@
+from lettucedetect.detectors.base import BaseDetector
+import re
+
+
+class NumberDetector(BaseDetector):
+    """Detect hallucinations only if a number appears in the answer not mentioned in the context."""
+
+    def predict(
+        self,
+        context: list[str],
+        answer: str,
+        question = None,
+        output_format: str = "tokens",
+    ) -> list:
+        """
+        Detect number hallucinations by comparing numbers in the answer with the context.
+
+        :param context: A list of context strings.
+        :param answer: The answer string.
+        :param output_format: 'tokens' for word-level or 'spans' for sentence-level results.
+        :return: List of hallucinated spans or tokens.
+        """
+        context_text = " ".join(context).lower()
+        hallucinated_numbers = self._detect_number_hallucinations(context_text, answer)
+
+        if output_format == "tokens":
+            return self._get_token_level_predictions(answer, hallucinated_numbers)
+        elif output_format == "spans":
+            return self._get_span_level_predictions(answer, hallucinated_numbers)
+        else:
+            raise ValueError("Invalid output_format. Use 'tokens' or 'spans'.")
+
+    def _extract_numbers(self, text: str) -> set:
+        number_pattern = r'\d{1,3}(?:,\d{3})*(?:\.\d+)?|\d+\.\d+|\d+'
+        return set(re.findall(number_pattern, text))
+
+    def _detect_number_hallucinations(self, context: str, answer: str) -> set:
+        context_numbers = self._extract_numbers(context)
+        answer_numbers = self._extract_numbers(answer)
+        return {num for num in answer_numbers if num not in context_numbers}
+
+    def _get_token_level_predictions(self, answer: str, hallucinated_numbers: set) -> list:
+        results = []
+        for match in re.finditer(r'\b\w+\b', answer):
+            token = match.group()
+            is_hallucinated = token in hallucinated_numbers
+            results.append({
+                "token": token,
+                "pred": int(is_hallucinated),
+                "prob": 1.0 if is_hallucinated else 0.0,
+            })
+        return results
+
+    def _get_span_level_predictions(self, answer: str, hallucinated_numbers: set) -> list:
+        spans = []
+        for match in re.finditer(r'[^.?!]+[.?!]', answer):
+            sentence = match.group().strip()
+            sentence_numbers = self._extract_numbers(sentence)
+            if any(num in hallucinated_numbers for num in sentence_numbers):
+                spans.append({
+                    "text": sentence,
+                    "start": match.start(),
+                    "end": match.end(),
+                    "confidence": 1.0,
+                })
+        return spans
+
+    def predict_prompt(self, prompt, answer, output_format="tokens") -> list:
+        """Predict hallucination tokens or spans from the provided prompt and answer.
+
+        :param prompt: The prompt string.
+        :param answer: The answer string.
+        :param output_format: "tokens" to return token-level predictions, or "spans" to return grouped spans.
+        """
+        return self._predict(prompt, answer, output_format)
+
+    def predict_prompt_batch(self, prompts, answers, output_format="tokens") -> list:
+        """Predict hallucination tokens or spans from the provided prompts and answers.
+
+        :param prompts: List of prompt strings.
+        :param answers: List of answer strings.
+        :param output_format: "tokens" to return token-level predictions, or "spans" to return grouped spans.
+        """
+        return [self._predict(p, a, output_format) for p, a in zip(prompts, answers)]
\ No newline at end of file
diff --git a/scripts/number_dataset_creation.py b/scripts/number_dataset_creation.py
new file mode 100644
index 0000000..7e997e4
--- /dev/null
+++ b/scripts/number_dataset_creation.py
@@ -0,0 +1,41 @@
+import re
+import json
+from concurrent.futures import ThreadPoolExecutor
+
+def extract_numbers(text):
+    """Extract all numbers (integers and floats) from the text."""
+    return set(re.findall(r'\d+(?:\.\d+)?', text))
+
+def is_hallucinated_numbers(batch):
+    """Return True if batch contains a hallucinated number."""
+    context = batch['prompt']
+    answer = batch['answer']
+
+    context_numbers = extract_numbers(context)
+    answer_numbers = extract_numbers(answer)
+
+    hallucinated = [num for num in answer_numbers if num not in context_numbers]
+
+    return bool(hallucinated)
+
+def filter_batches_with_hallucinated_numbers(dataset):
+    """Filter batches with hallucinated numbers in parallel."""
+    filtered = []
+    with ThreadPoolExecutor() as executor:
+        results = list(executor.map(is_hallucinated_numbers, dataset))
+    for batch, has_hallucination in zip(dataset, results):
+        if has_hallucination:
+            filtered.append(batch)
+    return filtered
+
+# Example usage:
+if __name__ == "__main__":
+    # Load your dataset here (replace with actual loading if reading from file)
+    with open("../data/ragtruth/ragtruth_data/.json", "r") as f:
+        dataset = json.load(f)
+
+    hallucinated_batches = filter_batches_with_hallucinated_numbers(dataset)
+
+    # Save the filtered hallucinated-number-only dataset
+    with open("hallucinated_numbers_only.json", "w") as f:
+        json.dump(hallucinated_batches, f, indent=2)
diff --git a/scripts/token_generation_simulator.py b/scripts/token_generation_simulator.py
new file mode 100644
index 0000000..1b6d348
--- /dev/null
+++ b/scripts/token_generation_simulator.py
@@ -0,0 +1,39 @@
+import re
+import json
+
+from lettucedetect.detectors.number import NumberDetector
+
+def simulate_llm_generation(batch, detector: NumberDetector):
+    context = [batch["prompt"]]
+    gold_answer = batch["answer"]
+    tokens = re.findall(r'\b\w+\b|\S', gold_answer)  # Better token splitting
+
+    # print(f"\nSimulating generation for:\nPrompt: {batch['prompt']}\n")
+    # generated = ""
+
+    for idx, token in enumerate(tokens):
+        token_preds = detector.predict(context, token, output_format="tokens")
+        hallucinated = [pred for pred in token_preds if pred['pred'] == 1]
+        if hallucinated:
+            print(f"[Step {idx+1}] Token: '{token}' -> Hallucinated Number Detected!")
+        else:
+            print(f"[Step {idx+1}] Token: '{token}'")
+
+    # print("\nFinal Answer Generated:\n", generated.strip())
+
+if __name__ == "__main__":
+    # Load data
+    with open("../data/ragtruth/hallucinated_numbers_only.json", "r") as f:
+        dataset = json.load(f)
+
+    # Instantiate the hallucination detector
+    detector = NumberDetector()
+
+    # Simulate LLM generation on one example for debugging
+    simulate_llm_generation(dataset[2], detector)
+
+
+    # Run over every experiment 
+    # Suggestion to comment else-statement in method and add break in if-statement
+    # for batch in dataset: 
+    #     simulate_llm_generation(batch, detector)
\ No newline at end of file