Opus 5 aces 20-digit multiplication; speculation on why no-thinking modes are withheld
scaling01 · x · 2026-09-17
A simple eval by maksymandr shows Claude Opus 5 hits 100% accuracy (1200/1200) on multiplications up to 20x20 digits, but only at max reasoning—a useful probe for no-CoT capability, especially for recurrent-depth architectures like GPT-6 Astra. scaling01 speculates Fable and Astra lack a no-thinking mode because it would leak hints about model size and depth, widen the attack surface, and risk a weak non-CoT Fable breaking the hidden-Fable-CoT mechanism.
Related event: Claude Opus 5 Aces 20×20-Digit Multiplication, 1200/1200 Without Tools(7 posts)→
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