178 Appendix A: The Automatic Memory Stack

Keystrokes

84000

§

§

§

Display

 

84,000.Enters base amount into displayed

 

X-register.
168,000.00Annual sales after first year.
336,000.00Annual sales after second year.
672,000.00Annual sales after third year.

In the example above, the constant was repeatedly multiplied by the result of the previous operation, which was already in the displayed X-register. In another class of calculations with constants, the constant is multiplied by (or added to, etc.) a new number keyed into the displayed X-register. For these calculations, you must press Obefore keying in a new number after having pressed an operator key. If this were not done, the stack would lift when you keyed in a new number after pressing the operator key, and the Y-register would no longer contain the constant. (Recall — from page 172 — that the stack does not lift when a number is keyed into the displayed X-register after Ois pressed.)

Example: At Permex Pipes a certain pipe fitting is packaged in quantities of 15, 75, and 250. If the cost per fitting is $4.38, calculate the cost of each package.*

Keystrokes

4.38\\

\

15

§

O75

§

O250

§

Display

4.38Enters constant into Y-, Z-, and T-registers.15.Enters first quantity into displayed X-register.

65.70Cost of a package of 15.

75.Clears display and enters second quantity into displayed X-register.

328.50Cost of a package of 75.

250.Clears display and enters third quantity into displayed X-register.

1,095.00

Cost of a package of 250.

*You may want to compare this method of arithmetic calculations with constants to the method using F described on page 74.

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Printered Date: 2005/7/29

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