What are you trying do? Do you want to have this figure when you Mass Update or while you add record? Both the ways it could be done.

First of all you need to put a counter field. You can use on Entry Form event 

If @IsNew and Counter ="" then
               {
                       counter = @number
                }

  Say you have four items on a form:

Item1
Item2
Item3
Total = Item1 + Item2 + Item3

Add one more element:

GrandTotal:

All of them formatted either Money or Number whatever you need to have.

I take it that you had item1.....Total  elements already there and now you added GrandTotal and Counter elements.

Select all records and sort it as you need to ( I am sure you have other fields on the form also, if not does not matter)

In Mass Update Spec:
Counter = @number
GrandTotal = Total + @xlookupr (@filename, counter-1, "counter", "GrandTotal")

This will give value to all the fields in your database in the existing records.

Now you want to set it up so, everytime you add a record and as you enter the last item, that is item3, you want to see the Total and GrandTotal

Following code goes in Item3 on ElementExit event:

Total = item1 + item2 + item3

GrandTotal = item4 + @xlookupr (@filename, 999999999, "counter", "GrandTotal")

/*this statement will lookup value GrandTotal in the next highest value of counter (Next less that 999999999, that will be the highest number in the existing records
*/

I believe this should work.

If you are working with the same application and you are looking up value in the application you are working, @filename means the same application. Suppose you are working on Customer.db, and looking value in external application named Vendor.db,  you will enter application name as "data\vendor.db".

Here it is internal lookup, lookup in the same application.

Mathewv,

The programming suggested above is works well. I have made a test application that I will send it to you if you request so.

Threre are a couple of small issues that I am reporting today.

1. The Programming in the last element does not execute even after using a tab key. I realize that it has no where to go.  But then you put goto command and it still would not go anywhere.  The only way to execute the command is to use mouse to move out of that field. I believe, the tab key should execute the element exit event command and goto command should also be executed in the last element of the database.

2. When you xloolup money field, it reads and gets value as text. You have to convert back into money to carry out further calculation. May be it is supposed to work that way or is it a bug?

Bharat,
It will be of great help if a small example file is made and sent to me.
Regarding"it has no where to go", I think if another field is made just for the cursor to move when tab is pressed, the grantotal field can function as programmed.
Thank you for the help.

does anyone know how to calculate a total of "Amount" fields for all records with the same ID?

I would like to calculate the total upon adding/updating a record.  The catch is that the Total field is on a Main form and the Amount field is on a subform.  I want to calculate this total and display it in Main once a change has been been to the Amount field on the subform. 

Why is Total in Main and not in the subform? B/c I don't see why I need a total field in the subform database. I just want to add up all the Amount field values for a client with a particular ID.

If I am not explaining myself well enough, here are my DBs:

Main:
Client ID, Name, Address, etc

Subform:
Client ID, Policy No, Amount

This is such b/c I can have many Policies and their corresponding amounts for one client.  Now, the question is, how to calculate all the amounts in the Subform for a particular client.

Sorry for the wordiness