Why won't Single take my number?

[Janie]

I have a field with NUMBER datatype, SINGLE field size, Fixed format and 0
Decimals. When I enter the value 100317090407 the number rewrites itself as
100317100000. When I enter 100317090417 again I get 100317100000. When I
enter 100317090499 once again I get 1003617100000.

My number is clearly under then max for a Single 3.402823E38, so what is
going on?

If I set my field size to DOUBLE, I do not encounter the same problem, but I
don't get it. Why do my numbers seem to have a mind of their own with the
SINGLE field size?

 

[Allen Browne]

Single is a floating point number, with only around 7 significant digits.

Use Double, or Decimal.

 

[Jeff Boyce]

Janie

Which version of Access?

Where are you doing this? (directly in the table, via a form, ??)

More info, please...

Regards

Jeff Boyce
Microsoft Access MVP

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[Janie]

Hmmm ... when reading the description of Single it sounds w-a-y different!
Up to seven decimal places and a maximum value of 3.402823 ^ 38

I get it ... I had already decided to go with Double .. but I wanted to
understand the why of the behavior.

So, bottom line is even though the maximum value is significantly higher, if
I want something grater than a 7 digit number, stay away friom Single.

Thanks for the enlightenment!

 

[John W. Vinson]

If I set my field size to DOUBLE, I do not encounter the same problem, but I
don't get it. Why do my numbers seem to have a mind of their own with the
SINGLE field size?

The Single datatype does indeed have a range to 10^38 or so... but it only has
24 bits of precision, equivalent to about 7 digits.

If these values are some sort of identifier, i.e. a part number or the like,
and you're not going to be doing any math calculations with them, you would be
much better off storing them in a Text field (with an input mask to force all
digits if that's what you want). This is doubly the case if you want leading
zeroes.

 

[Fred]

Or, to put it structurally, there are two lmitations:

1. Numerical size of the number

2. # of digits of precision.

What you were trying to do complied with #1 but violated #2.