Originally Posted by jhawkkw
That is one way to show repeating decimals, but the ellipses "..." is also widely accepted in mathematics to signify a repeating sequence.
The way I was taught mathematics and composition, an overline
placed above the sequence is used to indicate a repeating sequence, and the ellipsis is used in composition (writing) to indicate that text has been skipped. An ellipsis can be used in mathematical notation for the same purpose as with composition, but isn't interchangeable with the overline. But because many websites and other Internet services don't offer the entire range of possible characters, substitutes for full mathematical notation are often used for convenience.
When it comes to decimal numbers like a string of nines to the right of the decimal, you can either round up to a solid 1 or accept that adding more nines will approach but never reach 1.