The Addition function in the Survey123 Connect for ArcGIS 1.6 app appends the input values instead of summing them up correctly if the first input field is blank or if there are any input fields skipped and left blank.
Make all input fields as required fields, and provide the hint, 'Enter the value zero (0) instead of leaving it blank'.Alternative 1: Use the if-then-else statement in the calculation to force '0' to be calculated instead of supplied, for example: (if(${one}=0,1-1,${one}))+(if(${two}=0,1-1,${two}))+(if(${three}=0,1-1,${three}))+(if(${four}=0,1-1,${four})).Alternative 2: Cast the field values as integers so that Survey123 treats the fields as numbers instead of strings, for example: int(${field1})+int(${field2}).