You can order the vars in the HP48 menu typing 

VARS SORT ORDER and pressing [ENTER] 

You can define the numbers of mines in theMINEHUNT game. 

Store a number in the var Nmines , N in capital and the others letters in small case. 
This number will be the new number of mines. If you store a negative number in the var Nmines the mines become visibles. 

1-Begin removing the battery that is in the middle. 
It will make the work easier. 
2-To avoid confusion ( as risk of reuse an old batt) remove all old batts and separate it. 
3-Now get the new batts and replace. 

* Be carefull, dont put new batts together with old ones. 

Type: #9d SYSEVAL and press [ENTER] 

and... Hasta la vista babe! 
All the user memory will be deleted. 

* Danger! Do it only if you need. You was noticed! 

Press: ARG and the file will appears in the stack. 
So press [STO] and the VAR will be restored  
with the original name. 

* Advice! This only works if the LAST STAK is ENABLED. 
In this case, keeping the last stack enabled helps 
many users to recover purged vars. 
It doesn't work with directories. 

When you are editing a program press:  or  

The cursor will move to the bottom or to the top of the program. 

* More...  
Using the RIGHT SHIFT and the arrow sets RIGHT and LEFT the cursor goes fast to the first or to the last character in a line. 

For example: 
Put the matrix [ [1 2] ] [3 4] ]on the stack. 
Type DET and press [ENTER] 
Result: - 2 

* More...  
Using 1/X you can also invert square matrixes. 
This works for square matrixes of all order. 
It is limited only by memory. 

For example, lets integrate:  
It says 0.035033971515, after 43 seconds. 
Settinng format to 2 FIX we get Result: 0.03, after 4 seconds. 
Put now the format to STD to have full digits. Result: 0.0346435195954. 
The precision difference between both calculus is 
0.039041%, in this case. 

For example, create the directory DIR1:  
Put in level 1: 'DIR1' and type CRDIR and press [ENTER] 
The directory 'DIR' will be created. 

Now lets use a similar command to purge it. 
Put in level 1: 'DIR1' and type PGDIR and press [ENTER] 
The directory 'DIR1' will be purged.

You can easily delete the anoing numbers that appears 
in the top of the screen.  

They usually appears when you runs a program of the EXAMPLES LIBRARY. That examples accessed with the 
TEACH command. 

To get free of them execute {1 2 3 4 5} CF [ENTER]

Type: 
«CLLCD "TEXT1" 1 DISP 0 WAIT "TEXT2" 1 DISP 0 WAIT»  

Repeat "TEXT" 1 DISP 0 WAIT with the text you wish and how many times you wish. It will work as a single text viewer.

Type { VAR1 VAR2 VAR3 VAR4 } press [ENTER]  
and press [PURGE] 

Where VAR1, VAR2, VAR3 and VAR4 are the name 
of the vars to be purged.

Many trancendent equations like y=sin(x) for example 
has infinite roots. Using solve it will find a root, in many cases not the one you need.  
Give it a number in the field of the vars xand it finds the root closest to this number. 
For example 'sin(x)=5' given x in radians 
It says:1.57079629421 
Now put 6 in the field x. It says: 7.853981165738 
This is the other root of this equation. 
Give it a number and it finds the root closest to this number.

If you have an equation in level 1 , 'sin(x)' , for example 
Press  [EQUATION] and  [RCL]  

and the equation will appears in the EQ. Writer.

Press [VAR1] and type 'VAR2' [STO] 

Where [VAR1] is the name of the original VAR in menu  
and 'VAR2' the name of the duplicate new VAR. 

More...  
You can also press [VAR1]  
to edit it and save it with a new name. 

Type -40 CF and the clock will be visible. 

Type -40 SF and the clock will be invisible. 

More...  
You can try this also with other flags. 

1 - enters the matrix writer 
2 - press the softkey  or   
3 - enter numbes and press [ENTER] . 
For example: 1 2 3 4 5 6 7 8 [ENTER]  
4 - dont forget the space [SPC] between the numbers

For example: 
Lets evaluate the function y=sin(x)*cos(y)*ln(z) 
for x=5, y=4 and z=3 

1 - put y=sin(x)*cos(y)*ln(z) in level 1 
2 - type { x 5, y 4, z 3} and press [ENTER]  
3 - press  [SYMBOLIC] [NXT] [ | ]  
4 - result:0.688604398373 ( with angle mode in radians) 

For example. 
Lets calculate all roots of the polonomial X^4 - 10X^3 + 35X^2 -50X +24 
1 - type : [1 -10 35 -50 24] , type PROOT and press [ENTER]  
Result: [1 2 3 4] 
2 - using [1 2 3 4] and the comand [PCOEF] [ENTER] you can find the coefficients of the polinomial 
For example:[1 -3 1 5] [PCOEF] [ENTER] 
4 - result: [ 1 -5 -7 41 -30 ] or X^4 - 5X^3 - 7X^2 + 41X - 30

For example: 
3*x + 5*y - 3*z^2 - x+2*y - z^2  
1 - put on level 1: '3*x + 5*y - 3*z^2 - x+2*y - z^2 ' 
2 - type COLCT and press [ENTER]  
3 - result: '-4(4*z^2) +2*x+7*y' 

More...  
This operation can be repeated several times according to the complexibility of the expression.