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Start with the full category, then apply the exact boundary: The four new prefix names. Use the word, not the case-sensitive symbol; ronna and ronto have opposite scales. You only need one qualifying answer. A longer name is not automatically rarer.
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Shortest accepted input at 65+ points
RontoRonto · 85 points · 5 characters
Ronto denotes 10 to the power −27; its symbol is lowercase r.
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Quecto90 points · Shortest accepted spelling: Quecto
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- Base units and derived units are different sets. Follow any symbol-length restriction in the question; adding a metric prefix does not create another base unit.
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Each entry belongs to the bounded set defined by the prompt. The named source supports the underlying facts; our editorial scoring is a separate layer.
Source: BIPM · New SI prefixes, 2022 ↗
Reference version: 2026-10-21. See our answer policy for how we handle aliases and omissions.