This math scares me

Terry Reedy tjreedy at
Wed Mar 14 21:46:02 CET 2001

"Grant Edwards" <grante at> wrote in message
news:7bQr6.644$lz1.17686 at
> In article <98ohuc$du9$1 at>, Terry Reedy wrote:
> >> Bill Gates got this right in the early days, delivering two Basic
> >> interpreters:  binary floating point for speed, and decimal floating
> >> point for money and such
> >
> >If one counts pennies instead of dollars, then 32 bit ints (+- $20
> >will serve for many purposes.   Exact, faster, and more widely available
> >than BCD
> In fiancial calculations you also need to represent numbers
> that aren't amounts of money.  Interest rates for example.

So?  Floats (double precision) work well enough for this, I believe.

Note that binary fraction stock prices are exact with floats and not with

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