Often when writing we would like numbers to be written out fully e.g. thirty rather than in digits e.g. 30. Is there a name for this kind of representation?
The phrase spelled out is sometimes used; eg,
In your paragraph, spell out the digits under 10.
This usage is from the sense “To write or say the letters that form a word or part of a word” or the sense “Of letters: to compose (a word)” of the verb spell.
Longhand is the word I have heard used for this, though the definition does not specify the writing out of numbers.
The traditional terminology, in the days when proofreaders had to communicate with typesetters was set full out, which was the same term that was used when abbreviations were to be set out in full. This was needed so often that the abbreviation s.f.o. was recognized.
However, I cannot find any sources that show this is still in use so I think it must have gone out when typesetting using hot metal ceased to be part of the process.
The modern term for this is spelled out, abbreviated to sp. This is shown in various proofreading guides without an explanation of exactly what is meant but Vappingo proofreading symbols gives an example where a numeral is marked as sp where it is to be written as words.
So that means that spelled out (abbreviated to sp) appears to be the term generally accepted by proofreaders.