Section 3: The Memory Stack, LAST X, and Data Storage 35

The LAST X Register and K

The LAST X register, a separate memory register, preserves the value that was last in the display before execution of a numeric operation.* Pressing K (LAST X) places a copy of the contents of the LAST X register into the display (X-register). For example:

 

 

 

 

 

lost

 

 

 

 

 

 

T

t

 

t

 

z

 

 

 

 

 

 

Z

z

 

z

 

y

 

 

 

 

 

 

Y

y

 

y

 

16

 

 

 

 

 

 

X

4

 

16

 

4

 

 

 

 

 

 

Keys:

 

x

K

LAST X:

/

4

4

The K feature saves you from having to re-enter numbers you want to use again (as shown under Arithmetic Calculations With Constants, page 39). It can also assist you in error recovery, such as executing the wrong function or keying in the wrong number.

For example, suppose you mistakenly entered the wrong divisor in a chain calculation:

Keystrokes

Display

287 v

287.0000

12.9 +

22.2481

K

12.9000

Oops! The wrong divisor.

Retrieves from LAST X the last entry to the X-register (the incorrect divisor) before + was executed.

*Unless that operation was ’, S, or L, which don’t use or preserve the value in the display (X-

register), but instead calculate from data in the statistics storage registers (R2 to R7). For a complete list of operations which save x in LAST X, refer to appendix B.