Hi Belle,
As the previous post mentions, this is often caused by calculating a value
that does not fit into the fields number type. In queries, Access will
define the output number type based on the types of numbers being used in the
expression, but this isn't always what you want. You can use the numeric
conversion functions, such as CLng() and CDbl() to force the number field
size to what you want.
One other idea, I believe that dividing by 0 can also cause the overflow
error.
HTH, Ted Allen