multiplying multiple Fields in a form

[Dacho]

I have 4 fields with data that i want to multiply to get a volume in the capacity field

Length Width Depth (3): I know that if i multiply the three in the control source for capacity i can get the volume

and

Depth and Diameter (2): I know if i multiply these two in the control source for capacity i can get the volume.

I don't want to have two capacity fields in the table i am populating using the form.

Can somebody please help me with an if then statement or method that will multiply only the length x width x depth to calculate a volume (and only multiply these values diameter is empty)

conversely

if only depth and diameter are entered (length and width are empty) these values multiply together to give a volume.

Mainly want to stay away from having two capacity fields

Thanks in advance

If there is a way to do this in the tables that would be even better. using multiple columns to populate an empty column.

 

[gemma-the-husky]

depth times diameter isnt volume

depth times pi radius squared is volume (of a cylinder)

 

[wiremonkey22]

Why not use a Combo box to change the code like
if me.cboCalculation = LWD then
'calculate Length width depth'
else
'calculate Depth Diameter'
end if

 

[wiremonkey22]

Sorry "LWD" forgot the quotation marks