Definition:Repunit/Index

Definition

The index of a repunit is the number of digits it has.

Thus a repunit with $n$ digits can be referred to as $R_n$.

Linguistic Note

The derivation of the term repunit is clear: it comes from repeated unit.

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $1,111,111,111,111,111,111$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $1,111,111,111,111,111,111$