1 ENTER 3 / 3 * 1 -

[walter b]

1/3 = 0.333...3 (the number of digits depends on the respective calculator). Take this and multiply by 3 and you'll get 0.999...9 instead of 1. Subtracting 1 will result in -1 ULP, e.g. -1x10^(-16) on the WP 34S. So far, everything is perfectly ok on this calculator as well as on every HP calc I know.

Others will know more about TI.

d:-)