The number of outputs does not affect the accuracy or precision of each one. Whether the expression is expanded or not, the theoretical limit of the accuracy of a binary converter with n bits of input or output is one part in 2^n (two to the nth power). If your calculator has a button for this, you do not need to do it the long way.
Note that this is the theoretical limit of its accuracy. Other real world factors such as the precision of its internal resistor networks can reduce the ENOB - Effective Number Of Bits.
ak
Are you talking about a DAC with differential outputs like a DAC-08?
OK. That is not much information but it does look like it has differential outputs. Look at an Mc1408 or DAC-08 data sheet to see the difference in resolution using single-ended verses differential outputs.this is the DAC i was referring to. it wasn't made clear of the full method of calculating the resolution.