HP 15c - Manual (Page 41)

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
generation.
Z c c
Y c c Drops to interact
with X-register.
X 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.
vv
v 1.1500
Filling the stack.
1000
1,000
Initial culture size.