Formula Help Request

Do you not have a need to show Numeric Field 6? Such as if Numeric field 6 is not empty show it? 

In that case I would do: 

if( 

     not isnull(field 6), field 6,

     not isnull(field 5), field 5,

     not isnull(field 4), field 4,

     not isnull(field 3), field 3,

     not isnull(field 2), field 2,

field 1)

If you don't care about the value of field 6 and actually want to blank it out if its present, easiest way I'd suggest would be: 

if( 

     not isnull(field 6), null,

     not isnull(field 5), field 5,

     not isnull(field 4), field 4,

     not isnull(field 3), field 3,

     not isnull(field 2), field 2,

field 1)

Both formulas are reading it that in descending order of fields 5 to 1 that the first time it finds a value then it stops and keeps that value. You should also ensure that you either 1) are enabling that blank values mean null instead of 0 in the settings OR you can convert the formula to use the NZ() != 0 syntax. So instead of: 

not isnull(field) you would use Nz(field) != 0