3.1a The effect of the number sign.

The effect of the number sign is not terminated by intervening commas, colons, or hyphens (or fraction lines or decimal points, which will be studied later). Examples:

1,000,000

8:30

1850-57

A space or a mark of punctuation other than a comma, colon, or hyphen will terminate the effect of the number sign. Therefore, if a space or such punctuation falls in the middle of a number, the number sign must be repeated. Examples:

1 800 534-8765

We eat at 8:008:30 is too late.

1910?-1917

6(18)4