As with other tools, I tend to collect calculators and then scatter them all over. I live in the 2nd floor of a building, have a garage and an attic. Between home, car and work, I hate to have to go back to get something I need and forgot, so I have duplicates (triplicates...) of some tools I usually need. Assorted screwdrivers, pliers, multimeter... in some cases a calculator, is such of those things.
Even though, I install in all my computers, some of the free HP calculator emulators, it's not very practical to keep mouse clicking on the calculator buttons. I may use the windows calculator on occasion, Excel or Microsoft Mathematics and once in a wile some online dedicated calculator for things like filters, 555, LM317...
In conclusion. I have a lot more calculator options than brains.

Gathered all my current calculators for a photo family.

I have a few more at home, from wife and kids. From memory... HP19B II, HP10S, HP39G II, Casio FX-350ES plus, Casio FX-82MS, Casio FX-991SPX, Casio FX-82SPX, Casio FX-570SPX
Out of curiosity, one of this days
run a test on some calculators at home
Integral of
ln(x^2)dx, from
-5 to
99 (EDIT: as can be seen in the photo, on Casio FX-991ES display)
Casio FX-991ES --------------------- 3m15s ------------- 717.9281095
Casio FX-991ES PLUS -------------- 2m56s ------------- 717.9281095
Casio FX-991W --------------------- 1m28s ------------- 718 (
by smithnerd)
Casio FX-991EX --------------------- 35s ----------------- 717.9281095
Casio FX-570SPX II ----------------- 35s ----------------- 717.9281095
Casio fx-9750GII -------------------- 7s ------------------ 717.9281094 (
by Prehistoricman)
HP50g --------------------------------- just seconds ------ 717.928109451 (
by David Hess, "After resetting various CAS parameters")
HP 39G II ----------------------------- 7s ------------------- 717.928109451
HP 49G+ ------------------------------ 25m 38s ----------- 717.928325369
HP 40GS ------------------------------ 20m48s ------------ 717.928325369
HP 49G -------------------------------- 54m54s ------------ 717.928325369
HP 48G -------------------------------- 53m40s ------------ 717.928325369
HP 39GS ------------------------------ 20m28s ------------ 717.928325369
HP35S -------------------------------- failed to compute due to the discontinuity (
by rsjsouza)
HP15C--------------------------------- 10m35s------------- 718.0021 (
by DrGeoff)
Microsoft Mathematics on a i5 --------------------- 0s ------------------- 717.9281094509898
48G emulated on Galaxy S8 (Droid48) ----------- 45s ----------------- 717.928325369 (
by rsjsouza)
When applicable, HP 40GS, 49G and 49G+ had to be configured for complex and approximation mode, otherwise they couldn't solve. Hence the difference in the results from the 4th decimal digit.
HP 39G II (not in the photo) was a bit of a surprise. It was very fast. This calculator has a peculiarity I've never seen in any other battery powered device (excuse my lack of knowledge if that's the case). It has a compartment for 4 AAA batteries, but can run with only 1 AAA fitted.