HP HP-21 - Constant Arithmetic

26
J \J
Press Display
3
213
[x] (3 x .213)
=] 7.17 [B+4)+(5+2)+(4+3)]+(3x.213).
5 The first number is keyed in.
[x] 35.86 The answer.
You could also work this problem from left to right.
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Constant Arithmetic
You have probably noticed that whenever the stack drops be-
cause of a two-number operation (not because of @), the
number in the T-register is copied into the Z-register and also
rewritten into the T-register. This stack operation can be used
to insert a constant into a problem.
Example: Bacteriologist Martin Arrowsmith tests a certain
strain whose population increases by 15% each day under ideal
conditions. If he starts a sample culture of 1000, what will be
the bacteria population at the end of each day for six consecu-
tive days?
Method: Put the growth factor (1.15) in the Y-, Z-, and T-
registers and put the original population (1000) in the X-register.
Thereafter, you get the new population whenever you press[x].
1.15 Growth factor.
Growth factor now in T.
1000 Starting population.
(x] Population after Ist day.
[x] Population after 2nd day.
(x] Population after 3rd day.
[x] Population after 4th day.
[x] Population after 5th day.
[x] Population after 6th day.