Got my calculator to lie

[BruceZ]

I was under the impression that calculators are supposed to store enough hidden digits so that the digits on the display are accurate. My HP15C evaluates this:

1 / [1 - (1000000/1000001)^(1/37)]

as 37,037,037.04 when it should be 37,000,019. Excel and the windows calculator get it right.

What policy will guarantee that all digits are significant?