Format specifiers for function FormatFloat
0Forces digit display or 0
#Optional digit display
,Forces display of thousands
.Forces display of decimals
E+Forces signed exponent display
E-Optional sign exponent display
;Separator of +ve and -ve and zero values

Examples
Format string1234-12340.50
1234-12340.5 0
01234-12341 0
0.001234.00-1234.000.500.00
#.##1234-1234.5
#,##0.001,234.00-1,234.000.500.00
#,##0.00;(#,##0.00)1,234.00(1,234.00)0.500.00
#,##0.00;;Zero1,234.00-1,234.000.50 Zero
0.000E+001.234E+03-1.234E+035.000E-010.000E+00
#.###E-01.234E3-1.234E35E-10E0