This property defaults to 1 so that the value is used as is when being converted to a string. If the StringFormat was set to P0, a percent format which means the value is multiplied by 100, so when determining the new Value, the numeric value should be divided by 100 so the FromStringFactor might be set to '.01'. However if the Value was expected to be in the range from 0-100 then one might set the factor to 1.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2