The actual decimal and thousand separators depend on your system regional settings and the current Settings > Locales menu selection.

Max positive value: 1.7976931348623158e+308
Min positive value: 2.2250738585072014e-308
Precision: up to 15 digits

Use the Edit > Convert commands to convert numbers to text strings, and vice versa.

To force GS-Calc to treat entered data as a text label, press and hold SHIFT before pressing ENTER.

GS-Calc automatically converts text strings to numbers in formulas requiring numeric arguments, but only if they represent unformatted numbers using a period (.) as the decimal separator.

Example:
="1.5" + 1 -> valid
="1,500.00" + 1 -> #NUM!

Date/time/period values can be specified either as serial numbers or as generic date/time/period strings.

A date/time serial number is a floating point value representing a date between January 1, 100 and December 31, 9999. The integer part represents days; the fractional part represents time of day.

1.0 represents December 31, 1899.
Negative numbers represent dates prior to December 30, 1899.

A generic date/time string must conform to the www.w3.org specification.

For more information, see the Formula Composer window and included samples.

Note: To maintain maximum portability, you should use date serial numbers.

A four element 2x2 array:

{1, 2; "abc", "def"}

{1.00e+10; 2.00e+10; #N/A!; true}

Array elements may be unformatted numbers, text strings, Boolean values, or error codes.

With Settings > Locales > Generic:
Columns separated by commas (,)
Rows separated by semicolons (;)

With system regional settings using comma as decimal separator:
Columns separated by semicolons (;)
Rows separated by backslashes (\)