iFixit - Answers With Device "Casio FX-991ES Plus"

Casio FX-991ES Plus: My calculator is not turning on

Mon, 27 Apr 2026 14:31:31 -0700

How can i fix it

⟐ Commented April 27, 2026 at 14:31 MST

Casio FX-991ES Plus: Not working. No display. Better also changed. what should I do?

Mon, 23 Mar 2026 03:47:59 -0700

My Casio fx991 es plus calc not working what should I do? No display battery also changed. Advise me please.

⟐ Answered March 23, 2026 at 3:47 MST

Casio FX-991ES Plus: How to fix calculator suddenly goes off after calculation

Sun, 14 Sep 2025 05:15:30 -0700

As soon as I type any question and then press equal to it will give me the answer but it will suddenly go off in 5 seconds

⟐ Commented September 14, 2025 at 5:15 MST

Casio FX-991ES Plus: in dark place cannot see display

Wed, 09 Jul 2025 22:29:03 -0700

991es plus i bought 13years ago, now i use it to change the battery but lighting strong place there can use it. no lighting dark place cannot see the display but its working. how should i do?

Casio FX-991ES Plus: Facing Problem on my calculator

Mon, 02 Jun 2025 01:05:08 -0700

⟐ Edited June 02, 2025 at 1:05 MST

Casio FX-991ES Plus: Facing Problem on my calculator

Sun, 01 Jun 2025 23:52:08 -0700

My calculator is fully reversed. The number is reversed. Everything is rotated into 90 degree. How can i fix this problem?

⟐ Answered June 01, 2025 at 23:52 MST

Casio FX-991ES Plus: How to repair the display

Tue, 08 Apr 2025 23:29:40 -0700

How to repair the display of a Casio FX-991ES Plus Calculator

⟐ Commented April 08, 2025 at 23:29 MST

Casio FX-991ES Plus: Why screen are suddenly off and turn on?

Wed, 05 Mar 2025 13:07:28 -0700

in my calculator ,while i type or click digit like 3 to 4 numbers the screen refresh automically ....i mean when i click my fourth or seventh number the screen auto refresh and all type on screen are being deleted...on the other hand sometimes screen not shown to me...if i click a digit for a while the screen shown to me then i press of the digit screen are off....i changed my battery...now what should i do? is this repairable?

Casio FX-991ES Plus: How to fix the calculator that failed down and doesn't wanna open agai

Mon, 28 Oct 2024 17:19:52 -0700

How to fix a calculator that failed down and doesn't wanna open again

Casio FX-991ES Plus: Calculator not working properly

Wed, 25 Sep 2024 09:41:18 -0700

I have casio fx99ies plus calculator. 3 days earlier i was using it when it turned off then i replaced its lithium battery but it won't start then i noticed that when i press the battery hardly it starts but when i release it, it stops . Kindly tell a solution to this problem

Casio FX-991ES Plus: How do I fix my calculator that only runs on solar power?

Sat, 23 Mar 2024 18:15:54 -0700

My Casio fx-991ES PLUS was dropped and now the display does not light up unless it is under a light source. It has a mini solar panel which I assume it using for power and it has new batteries in it but they do not seem to work. Is there something I can do to fix it?

⟐ Commented March 23, 2024 at 18:15 MST

Casio FX-991ES Plus: started working like that of Casio 115 ES plus.

Fri, 10 Nov 2023 18:25:59 -0700

I'm using Casio Fx-991EX class wiz. Suddenly the function started working like that of Casio 115 ES plus. It brought out Chinese instead of English and the keys aren't working well like it was doing before. (When I press Calc, box raise to the power of 3 is displayed

⟐ Edited November 10, 2023 at 18:25 MST

Casio FX-991ES Plus: My Casio power button is not working

Fri, 18 Aug 2023 19:35:59 -0700

All buttons work except the power button. If you ask me how do I know, I tried connecting the calculator to the power supply and my system worked.

⟐ Answered August 18, 2023 at 19:35 MST

Casio FX-991ES Plus: Why doesn't my calculator turn on though I just got it?

Sun, 07 May 2023 09:33:08 -0700

My calculator is new and has no faults i hav tried putting my calculator under my laptop and outside but it is not turning on so what should i do.

⟐ Answered May 07, 2023 at 9:33 MST

Casio FX-991ES Plus: My Calculator's [AC] & [-] buttons aren't working properly

Tue, 31 Jan 2023 16:09:12 -0700

I cannot turn it off, or reset it because my AC button doesn't budge. Meanwhile the minus button adds a number 1 in the equation whenever I press it. Please help! I really need this calculator. edit: my division button also adds 4 instead of the division sign.

⟐ Commented January 31, 2023 at 16:09 MST

Casio FX-991ES Plus: Can't find the brightness changer mode

Mon, 26 Dec 2022 01:35:21 -0700

I have Casio 991-MS calculator and have an issue to change my display brightness,when I switching with Mode key,I can't find Cont mode,while in another same calculator there is , anybody can help me with that quickly?

⟐ Answered December 26, 2022 at 1:35 MST

casio fx-991es plus: LCD has blotch after I dropped my calculator. Can this be fixed?

Fri, 16 Dec 2022 04:22:43 -0700

I dropped my calculator the other night and some faint cracks and a blue blotch runs vertical across the lcd. It still works but the numbers where the blue blotch is can't be seen. Can I fix this somehow? Or is it possible to have the lcd replaced?

⟐ Commented December 16, 2022 at 4:22 MST

Casio FX-991ES Plus: Why it is hang after pressing √(10) *10^13

Thu, 21 Apr 2022 03:22:03 -0700

How to unhang calculator

⟐ Commented April 21, 2022 at 3:22 MST

Casio FX-991ES Plus: calculator is switching off despite I changed the cells

Tue, 08 Mar 2022 17:13:04 -0700

My calculator is switching off whenever I'm doing any word problem involving fraction and complex calculator. I tried changing the cells it was however of no use

Casio FX-991ES Plus: My calculator is not turning on

Wed, 08 Sep 2021 01:35:53 -0700

My calculator is not turning on

⟐ Answered September 08, 2021 at 1:35 MST