Section 3: The Memory Stack, LAST X, and Data Storage 41

Loading the Stack with a Constant. Because the number in the T-register is replicated when the stack drops, this number can be used as a constant in arithmetic operations.

T

c

 

c

New constant

Z

 

 

 

generation.

c

 

c

 

 

Y

 

 

 

Drops to interact

c

 

c

X

 

 

 

with X-register.

x

 

cx

 

 

Keys:

 

*

 

 

 

 

 

Fill the stack with a constant by keying it into the display and pressing v three times. Key in your initial argument and perform the arithmetic operation. The stack will drop, a copy of the constant will "fall" into the Y-register, and a new copy of the constant will be generated in the T-register.

If the variables change (as in the preceding example), be sure and clear the display before entering the new variable. This disables the stack so that the arithmetic result will be written over and only the constant will occupy the rest of the stack.

If you do not have different arguments, that is, the operation will be performed upon a cumulative number, then do not clear the display—simply repeat the arithmetic operation.

Example: A bacteriologist tests a certain strain of microorganisms whose population typically increases by 15% each day (a growth factor of 1.15). If she starts with a sample culture of 1000, what will be the bacteria population at the end of each day for four consecutive days?

Keystrokes

Display

 

1.15

1.15

Growth factor.

vv1.1500 Filling the stack.

v

1000

1,000

Initial culture size.