?€123.456 + €23.55
0.456 0.55

My intuition was €123 and €23 were both valid parameter names. First char is neither numeric nor reserved prefix / suffix. To test this, in immediate window

€123=”poiuyt”
?€123.456 + €23.55 gives poiuyt{Space}0.456{Space}{Space}0.55

€123=”poiuyt”
€23 = “mlkjhg”
?€123.456 + €23.55 yields an error but

€123=”poiuyt”
€23 = “mlkjhg”
?€123.456 & €23.55 gives poiuyt0.456mlkjhg{Space}0.55

It doesn’t work with $ as US dollar symbol is a reserved suffix for string parameter.

Same behaviour for any non reserved chars (ANSI & UNICODE) map upto &hFF ie

?{Any non reserved char}123.456 + {Any non reserved char}23.55
0.456 0.55

Interesting… the “£” symbol attached to the front of a floating point number does the same thing on my “US Locale” computer as well; namely, return the decimal portion of the number. However, it seems to only work when physically attached to the number… I can’t find anyway to concatenate that symbol onto a floating point number (using CDbl, Val, Evaluate, etc.) in order to force it to return just the decimal part of the number.

Likewise the hash symbol ‘#’ has no value as a prefic – but it remains the delimiter around a date:

?

On a PC with the locale set to ‘United Kingdom’, our local currency sign ‘£’ does… Something. Try evaluating these expressions in the immediate pane and see what you get:

?£123
[returns an empty string]

?£123.456
0.456

?£123.000
0

?£123.456 + £23.55
0.456 0.55

So it seems to me that the Pound sign is some kind of type suffix – although it’s just as likely to be an undocumented operator.

I almost missed your ending question… yes, there is one other that I am aware of… &O or just a leading & by itself… this is an apparent throw back to ancient times as it will interpret the digits following it as Octal (only the digits zero through 7 may follow the &O or leading &).

It won’t work with versions before Excel 2007.