10/2/2019 Hack Casio Fx-991ex
Casio Scientific Calculator fx-991EX A new high-performance scientific with high resolution display increasing the amount of information displayed and super-fast calculation speed for high-stakes testing or for performing the most advanced mathematics. The TI-36X Pro is better than the Casio fx-991ex. Because once you change modes, or once your Casio auto times-out after a few minutes and shuts down, all of your calculation history is lost; gone; erased. That’s why I prefer the TI-36X Pro.
Aguilera Dario likes his Casio fx-82ES calculator. However, it was missing a few functions, including complex numbers. A Casio fx-991ES has more functions but, of course, costs more. A quick Google revealed that if you press the right buttons, though, you can transform an fx-82ES into an fx-991ES.Because it is apparently a buffer overflow exploit, the hack involves a lot of keys and once you cycle the power you have to do it again. Aguilera realized this would be a good candidate for automation and. You can see a video of a breadboard version below.
He also has a PCB version in the works that should be better integrated.Posted in Tagged,.
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This calculator does not have any modulo function. However there is quite simple way how to compute modulo using display mode ab/c (instead of traditional d/c).How to switch display mode to ab/c:.
Go to settings ( Shift + Mode). Press arrow down (to view more settings). Select ab/c (number 1).Now do your calculation (in comp mode), like 50 / 3 and you will see 16 2/3, thus, mod is 2. Or try 54 / 7 which is 7 5/7 (mod is 5).If you don't see any fraction then the mod is 0 like 50 / 5 = 10 (mod is 0).The remainder fraction is shown in reduced form, so 60 / 8 will result in 7 1/2. Remainder is 1/2 which is 4/8 so mod is 4.EDIT:As @lawal correctly pointed out, this method is a little bit tricky for negative numbers because the sign of the result would be negative.For example -121 / 26 = -4 17/26, thus, mod is -17 which is +9 in mod 26. Alternatively you can add the modulo base to the computation for negative numbers: -121 / 26 + 26 = 21 9/26 (mod is 9).EDIT2: As @simpatico pointed out, this method will not work for numbers that are out of calculator's precision. If you want to compute say 200^5 mod 391 then some tricks from algebra are needed.
For example, using rule(A. B) mod C = ((A mod C). B) mod C we can write:200^5 mod 391 = (200^3. 200^2) mod 391 = ((200^3 mod 391). 200^2) mod 391 = 98. As far as I know, that calculator does not offer mod functions.You can however computer it by hand in a fairly straightforward manner.Ex.(1)50 mod 3(2)50/3 = 7(3)7 - 16 = 0.66666667(4)0.66666667.
3 = 2Therefore 50 mod 3 = 2Things to Note:On line 3, we got the 'minus 16' by looking at the result from line (2) and ignoring everything after the decimal. The 3 in line (4) is the same 3 from line (1).Hope that Helped.EditAs a result of some trials you may get x.99991 which you will then round up to the number x+1. @Faizan this is a separate question/problem, try asking a question of your own (if it doesn't already exist). But the easiest method I find is to convert it to hexadecimal which then converts to binary instantly (i.e. Dec 10 = Hex A = Binary 1010). There are relatively simple methodologies to go between even very very big (or very very small!) exponential decimal values to hex, google 'em.
I had to use them in one of my first year CS exam questions. If you ever need to check the binary of anything, always work in hex rather than decimal anyway.–Oct 25 '15 at 5:55. It all falls back to the definition of modulus: It is the remainder, for example, 7 mod 3 = 1.This because 7 = 3(2) + 1, in which 1 is the remainder.To do this process on a simple calculator do the following:Take the dividend (7) and divide by the divisor (3), note the answer and discard all the decimals - example 7/3 = 2.3333333, only worry about the 2. Now multiply this number by the divisor (3) and subtract the resulting number from the original dividend.so 2.3 = 6, and 7 - 6 = 1, thus 1 is 7mod3. You method is correct and obvious, but impractical for most conditions where you would even need a calculator in the first place. In an exam for discrete math say, if you are trying to figure out congruence of very very large exponents then this method is directly impossible, and indirectly much too slow – you usually have to do a bit of RSA encrypt/decrypt in the exam by hand and without a built-in mod functionality it takes up too much time.
Even our lecturers tell us this. Not a criticism of your answer, just worth pointing out it's practical limitation.–Oct 25 '15 at 5:38.
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