Calculator reciprocal the reciprocal of 0.6

Use the key x-1.
Example: reciprocal of 5: Press 5, then key x-1, then =

To calculate the cotangent of an angle, calculate the angle's tangent and then take the reciprocal.
To calculate the angle given a cotangent, take the tangent's reciprocal then the arctangent.
If you're asking how to do this on a particular calculator, what make and model?

Your question is not clear. To calculate the reciprocal of a number on display use the x^-1 or 1/x key, or just enter 1/ number.

Enter the number and press the = sign.
With the number displayed, press the power key (marked as [X^y], [Y^x] or [^]) followed by exponent -1.
OR while the number is stored in Ans memory, enter 1 / Ans.
Some calculators have a special key for the reciprocal. It is marked as [x^-1]. By pressing the reciprocal key while number is displayed, you calculate its reciprocal.

It's the second function of the "2" key, marked "x-superscript-negative-one".

Not all matrices are invertible. The matrice must be square.The matrix must be non-singular: Its determinant must be different from 0. Your error comes probably from the key you used to calculate the inverse. Use the reciprocal key, the one marked with x^-1. If the marking is not ON the key, use the SHIFT button prior to pressing the relevant key.

To calculate the reciprocal of a numerical value you can use

1. 1 / numerical value or
   
2. use the key sequence [SHIFT] [ ) ] (X to -1), if the number is already displayed (stored in answer Ans memory)

Example: calculate the reciprocal of 13. Must be in Run Mode

1 [/] 13 [EXE] result is 0.07692307692 or

13 [EXE] to have 13 in Ans memory (displayed) and [SHIFT][ ) ] [X to -1] [EXE].

For such a simple number as 13, calculating its reciprocal the second way seems ridiculous, but if the number is already displayed the second method is the only efficient one if you do not want to copy the result on a piece of paper and retype so as to calculate its reciprocal.

Hello,
When you get the error press any key to suppress the error message. Put the calculator into PROGRAM mode and you will see the line where the error occurred.

Here is what the manual says for ERROR 4 (free translation)
The line number called is not used or does not exist (larger than 448); attempt to load a program line (instruction) where there is not enough space; line label inexistant.
My hunch is that you are attempting to divide by 0: The quantity of which you are taking the reciprocal (inverse function has another meaning) may have a 0 value.
Do not forget to check the input values.
Hope that will help you debug your program

sec 23

It does. For instance, to get the reciprocal of 4, enter the following sequence: 4 [1/x] (this last key to be found third row down, second black key in). The decimal 0.25 will appear as the result. Convert this, if you want, to the fraction 1/4 by pressing the yellow function key [2nd], then {F<>D] located bottom, far left. Hope that's what you wanted!