In a way that can be calculated or determined by mathematics; in a manner that is predictable or measurable.
From calculable plus the adverbial suffix -ly. The formation follows standard English patterns: adjective + -ly = adverb, allowing calculable to modify verbs and other adjectives.
The -ly suffix is one of English's most productive word-building tools, transforming over 10,000 adjectives into adverbs—but with calculably, you rarely hear it used in modern English, showing that not all grammatically possible words remain in common use.
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