calculate in form

[cram]

work with Xp and Access2003
I want to do following
In an Input form I want to check if some data aore correct. based on
invoices I introduce the BasicAmount, the txes and the total of the invoice
i.e. the sum of Basic + Taxes say i.e. 100 + 21 = 121
I intorduce the 100, the 21 and the 121. As matter of contol I compare the
calculated sum of 100+21 and compare with the inputed 121. If there is a
difference I show an error message.
My problem is now that for SOME records the message appears although the 3
inputs are correct.
As futher detail, all nummers are "single".
I'm afraid that in calculating "the sum" there must be some "distorsion"
somewhere in the decimal-figures.
Any one any idea?

 

[KARL DEWEY]

You need to show us what your formulas look like.

Also post examples of the 'distortion' you are getting, input and output
numbers.

 

[John W. Vinson]

work with Xp and Access2003
I want to do following
In an Input form I want to check if some data aore correct. based on
invoices I introduce the BasicAmount, the txes and the total of the invoice
i.e. the sum of Basic + Taxes say i.e. 100 + 21 = 121
I intorduce the 100, the 21 and the 121. As matter of contol I compare the
calculated sum of 100+21 and compare with the inputed 121. If there is a
difference I show an error message.
My problem is now that for SOME records the message appears although the 3
inputs are correct.
As futher detail, all nummers are "single".
I'm afraid that in calculating "the sum" there must be some "distorsion"
somewhere in the decimal-figures.
Any one any idea?

Since these values refer to money, I'd strongly suggest using the Currency
datatype rather than Number... Single. Single numbers are floating point
values; as such, some values cannot be represented accurately. 100 and 21
should work, but (for instance)

?csng(3.1) + csng(5.3) - 8.4
9.53674312853536E-08

Single *IS AN APPROXIMATION*, accurate to about 7 decimal places, and as you
see, not always exact!

Using Currency datatype avoids this issue:

?ccur(3.1) + ccur(5.3) - 8.4
0