Language Models Compare Quantities Using Number-specific and Unit-specific Heuristics
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Abstract (arXiv)
Quantities with measurement units, such as 110 cm and 1.2 m, require language models (LMs) to combine a numeral with a symbolic unit scale. Here, we study how LMs compare such quantities in controlled settings spanning several unit systems. We find that accuracy degrades near the comparison boundary, where small changes in value determine the correct answer. The resulting errors are systematic: linear surrogate models predict LM preferences from numerical-difference and unit-scale-difference cues, and causal interventions on subspaces aligned with these variables shift model's output. The results suggest that LMs compare quantities through a bag of heuristics over numerals and units, rather than first converting both expressions to an exact shared-scale representation.
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References · 16
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- 2025Language Models Use Trigonometry to Do Additioncited by 70
- 2024Interpreting and Improving Large Language Models in Arithmetic Calculationcited by 45
- 2024Pre-trained Large Language Models Use Fourier Features to Compute Additioncited by 39
- 2024Language Models Encode Numbers Using Digit Representations in Base 10cited by 32
- 2024Language Models Encode the Value of Numbers Linearlycited by 20
- 2024The Geometry of Numerical Reasoning: Language Models Compare Numeric Properties in Linear Subspacescited by 10
- 2024Understanding Addition and Subtraction in Transformerscited by 8
- 2024Survival of the Fittest Representation: A Case Study with Modular Additioncited by 7
4 more
- 2026LLMs Know More About Numbers than They Can Saycited by 7
- 2021Masked Measurement Prediction: Learning to Jointly Predict Quantities and Units from Textual Contextcited by 5
- 2025On Generalization across Measurement Systems: LLMs Entail More Test-Time Compute for Underrepresented Culturescited by 5
- 2023Enhancing Quantitative Reasoning Skills of Large Language Models through Dimension Perceptioncited by 4
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