HP 35s Extract Denominator from Fraction

[Joe Horn]

(08-11-2014 04:43 AM)bcode Wrote:  Hi,

Is there any way to extract the denominator (or numerator) from a fraction on the HP 35s? I'm trying to convert mixed fractions to improper fractions. It's a small thing but if it's possible I would appreciate any help.

No, it's not possible, since it's only a display mode, which means that the denominator that's displayed only exists in the display and is not available anywhere for calculations. (If anyone here knows differently, please post the method!)

However, here's a trivial trick that sort of "converts" mixed numbers to improper fractions: just press 1/x, and read the result upside down (as it were).

Example:
left-shift Display: ALL
left-shift pi
right-shift FDISP
--> see 3 16/113
1/x
--> see 113/355 (so the original = 355/113)
Thus we have "converted" 3+16/113 into 355/113.

Unfortunately, this "trick" occasionally fails for various reasons, like here:

7 sqrt
--> 2 2295/3554
1/x
--> 765/2024 (which means 2024/765, but we wanted 9403/3554).

What that happens, you have to do it manually, which is easy since the 35s has a two-line display:
If a+b/c is displayed, then:
Desired Numerator = c*a+b
Desired Denominator = c