Whenever I put in a simple equation like [NRtime]/[StTime], I get a the message that says "Overflow". What is that?

An overflow occurs when you assign a data type as one type and that data type cannot store that data because it is too large for the 'container' you assign. For instance you can do:

Dim byt as Byte
byt = 255

but you can't do:
byt = 256
or
byt = 25.5

because a byte data type will only hold integer values up to 255, to correct the above errors change the variable declarations to the appropriate types. Do a search on Data Type Summary in Access Help for direction as to which data type is appropriate.

In your case it sounds like your formula is returning a fractional value and you have the fields data type set to Integer or Long, try changing it to Single or Double and see how you get on.

Ian

You also need to be careful with division since if your divisor is equal to 0, you will get an error.