Reciprocal Where is the reciprocal key on my calculator? It is the TI-30XA

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

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.

Use the 1/x key or the general power key x^-1.
By hand 0.6=3/5
The reciprocal of 3/5 is 5/3

There are two solutions: 2/3 and -3.

If this is a homework problem, be sure to show your work.

There is a key on the left column of keys, below the MATH key and above the x^2 key. It is marked with an x raised to power of -1.
It computes the reciprocal of the number displayed.

There isn't a cosecant key. Use the relationship
 csc(x) = 1 / sin(x)

Compute the sine and take its reciprocal.

The cosecant function does not have a specific key on any calculator because it can be easily calculated as the reciprocal of sine.
Thus csc(-330°)=1/sin(-330°)=2
sin(-330°)=sin(360°-330°)=sin(30°)=0.5
csc(-330°)=1/0.5=2
If you do not want to be bothered with these facts, just calculate the sine of -330° and take the reciprocal of the result using the [x^-1] key. For the minus sign before 330, use the change sign key (-). Close the right parenthesis.

[SIN] [(-)] 330 [)] [x^-1]

There is no log (base 10) button on a TI-89. It's buried in the CATALOG as log(. As a shortcut, you can do ln(#)/ln(base), where # and base are replaced with what you want. For the inverse of a log, do the base raised to the part on the other side of the equals sign. So, log(x) = 2 would become 10^2 = x.

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!