Detailed Calculation Settings
Sets the rules for conversion from strings values to numeric values, string values to cell references, and strings values to date and time values. This affects builtin functions such as INDIRECT that takes a reference as a string value or date and time functions that takes arguments as string values in local or ISO 8601 formats.
Contents to Numbers
Conversion from text to number
How to treat text when encountered as operand in an arithmetic operation or as argument to a function that expects a number instead. Unambiguous conversion is possible for integer numbers including exponents and ISO 8601 dates and times in their extended formats with separators. Fractional numeric values with decimal separators or dates other than ISO 8601 are locale dependent. Note that in locale dependent conversions the resulting numeric value may differ between locales!
Generate #VALUE! error: Text found where numeric data is expected will generate #VALUE! error. Example: "123.45" will generate a #VALUE! error, while 123.45 not.
Treat as zero: Any text found where numeric data is expected will be considered as a number of value zero. Example: "123.45" will map to zero, while 123.45 not.
Convert only if unambiguous: If the text represents a valid and unambiguous numeric value, convert it. Example: "123.456" will generate a #VALUE! error because the text contains a separator, while "123456" will not.
See Converting Text to Numbers for details.
Convert also locale dependent: convert values valid in the locale representation. Example: "123,45" is a valid number in some locales because the comma is the decimal separator there.
Treat empty string as zero
This option determines how an empty string is treated when used in arithmetic operations. If you have set "Conversion from text to number" to either "Generate #VALUE! error" or "Treat as zero", you cannot choose (here) if conversion of an empty string to a number will generate an error or if it will treat empty strings as zero. Otherwise this option determines how empty strings are treated.
Reference syntax for string reference
Formula syntax to use when parsing references given in string parameters. This affects builtin functions such as INDIRECT that takes a reference as a string value.

Use formula syntax

Calc A1

Excel A1

Excel R1C1

Calc A1  Excel A1