Question

The number of digits in the recurring part is called ___​

Answer 1

A repeating decimal

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Answer 2

$\huge\bf\red{repeating \: decimal}$

The minimum number of digits that repeats in such a number is known as the decimal period. Repeating decimal notation was implemented in versions of the Wolfram Language prior to 6 as PeriodicForm[RealDigits[r]] after loading the add-on package NumberTheory`ContinuedFractions`.