Turns a number into a currency representation. You can select the :unit (denomination), :separator (normally .), :delimiter (normally , ), :format (whether the currency comes before or after the number), and :precision (normally 2).

Turns file-size byte counts into more typical human representations, like 12 GB.

Turns a number into a percent value. You can select the :precision (normally three digits after the decimal), and the :separator (normally .).

Turns a number into an American-style telephone number. You can specify a country code, extension, delimiter, and whether or not the area code has parentheses, but you can’t specify how the numbers are broken down.

Formats a number with a given :delimiter between thousands (, by default) and decimal :separator (. by default).

Formats a number to present as many digits after the decimal point as are specified in the second argument (three is the default).