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Q
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So I’ve decided to actually read the manual for my scientific calculator. I will post any interesting finds.

1)Percentage increase and decrease.
2) Ever wondered what that 3rd "mode" option meant?

Fix = fixes number of decimal places to display
Sci = rounds to significant digits (in scientific/standard form)
3) Pol(a,b) converts the rectangular coordinates (a,b) into polar coordinates. The displayed answer is the r value, to find the angle press RCL and the F.
4) Okay this model of calculator is pretty old, so after a little bit of stats stuff you'll just have to trust me on newer calculators (try it for yourself)!

Stats:
SD = calculations involving standard deviation
REG = calculations involving regression

E.g., [cont.]
5) in SD you input data points with inputting the values and then pressing DT. n = 4 here means I have put in four numbers so far.

You can then use the S-SUM and S-VAR buttons for the following information:
6) in REG, after choosing the model [e.g., linear, logarithmic, etc.], you input the data with comma as shown [don't forget to press DT].

S-SUM and S-VAR display more options, including the correlation coefficient r. Regression formula in increasing powers of x.
7) Now for some more advanced stuff - some older calculators (like mine) will not have these functions but I implore you to try these out using your calculators to see how they work. [cont.]
E.g., Prime Factorisation.

Input your number as usual, then press shift followed by the degrees, minutes, seconds button (°'''). Voilá
8) If you have the TABLE function you can generate coordinates (etc.) as follows:

i) Write the function f(x) = ... into your calculator [use alpha then X for the variable]
ii) = lower bound
iii) = upper bound
iv) = incremental steps.
9) What about the VERIFY mode? What's that all about?

Well, if you want to check if a statement such as "2 + 4 > 7" is true or false simply do the following:

2 + 4
SHIFT (choose VERIFY)
choose >
7

Calculator displays FALSE
10) Do your students ever get confused how to convert time? Either adding or what 2 and 1/4 hours is in hours and minutes? Then the degrees minutes seconds button is your saviour °'''

[cont]
E.g., to convert 2 and 1/4 hours into hours and minutes simply do the following:

2.45 then °'''

What about 12:40 + 3 hours and 45 minutes ?

What's 500 seconds in minutes and seconds?
Bet @CasioMaths is like 💁 "We did all of that"
11) But what about GCD and LCM?

Use fractions!

36/9 = 4 -> GCD(36, 256) = 4
36 * 64 = 2304 -> LCM(36, 256) = 2304
12) Want to find the equation of a straight line passing through two points?

Use linear regression!

E.g., between (2,2) and (3,5)

MODE -> REG -> Lin

2,2 DT
3,5 DT

S-VAR
A = -4
S-VAR
B = 3

Hence equation of the line is y = A + Bx i.e., y = -4 + 3x
<<May as well add>>

I collect maths materials (exams, questions, textbooks) from around the world - if anyone wants to donate some feel free to comment/message :)
14) A couple more percentage ones:

To find one value as a percentage of another simply divide the former by the latter and press SHIFT %

E.g., 45 is what percentage of 80?

45 ÷ 80 %
15)
To find *what* the percentage increase (or decrease) has been when increasing a value by another simply do the following:

added (or subtracted) amount + original value %
ANS - 100

(positive = increase, negative = decrease)
16) OR, equally, to find the percentage change you can do the following:

New value - Old value %

(positive = increase, negative = decrease)
17) Not as neat as I was hoping, but for a "reverse percentage" (finding the original after a percentage change) you can do the following:

New value ÷ (100 + percentage) %

Or if the value was decreased, such as in a sale:

New value ÷ (100 - percentage) %

E.g.,
18) Need to find the hypotenuse when given the shorter side lengths?

Pythagoras takes a few steps, you can utilise Pol(a,b) - e.g.,
19) However finding the shorter side lengths requires a bit more work with this approach, so maybe stick with the differences of the squares.
20) Updated thread based on the new #85GTX model of calculator -
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