Most impressive/complex/amazing C-series program?

[Dieter]

(08-12-2018 02:21 PM)Albert Chan Wrote:  Calculate B^2 - AC = 735246^2 - 11713 * 46152709

On my Casio, both B^2 and AC got R = 5405866805e2
The tenth digit (5e2) could be off. So, find out last 3 digits:

B^2 % 1e3 = 246 ^ 2 % 1e3 = 516 = 16 + 5e2 (matching R last digit)
AC % 1e3 = 713 * 709 % 1e3 = 517 = 17 + 5e2 (matching R last digit)

So, B^2 - AC = (R + 16) - (R + 17) = -1

For the record: such calculations with "extended precision" are easily done on the 35s using vectors. For instance, B^2–AC can be calculated via [B, –A]x[B, C]. This uses the internal 15-digit precision. No Σ+ tricks required. ;-)

Maybe something similar can be done on the 42s with complex numbers.

Dieter