HP 12C Financial 0012C-90001, 12C Financial 12C#ABA, 12C Financial F2231AA#ABA Arithmetic Calculations with Constants, 2, Display, Display, Example:, Keystrokes, Keystrokes

Appendix A: The Automatic Memory Stack 177

The diagram on page 171 illustrates how the automatic stack lift and stack drop make chain calculations quick and error-free.

Virtually every chain calculation you are likely to encounter can be done using only the four stack registers. However, to avoid having to store an intermediate result in a storage register, you should begin every chain calculation at the innermost number or pair of parentheses and then work outward — just as you would if you were doing the calculation manually (that is, using pencil and paper). For example, consider the calculation of

3 [4 + 5 (6 + 7)]

If this calculation were done from left to right — as were the (simpler) examples under Chain Calculations on page 20 and page 22 — you would have to enter five numbers into the calculator before doing the first operation possible (6 + 7). But since the stack holds only four numbers, this calculation cannot be done left-to-right. However, it can easily be done if you begin with the calculation in the innermost pair of parentheses — again, (6 + 7).

Keystrokes	Display
6\7+	13.00	Intermediate result of (6+7).
5§	65.00	Intermediate result of 5 (6+7).
4+	69.00	Intermediate result of [4 + 5(6 + 7)].
3§	207.00	Final result: 3 [4 + 5 (6 + 7)].

Arithmetic Calculations with Constants

Because the number in the T-register remains there when the stack drops, this number can be used as a constant in arithmetic operations. To place the constant into the T-register, key it into the display (that is, into the X-register), then press

\three times. This also places the constant in the Y and Z-registers. Each time an arithmetic operation is then performed — using the constant in the Y-register and a number keyed into the displayed X-register — the constant will be “dropped” back into the Y-register.

Example: The annual sales of solar engineering hardware your firm — currently $84,000 — are projected to double each year for the next 3 years. Calculate the annual sales for each of those years.

Keystrokes	Display
2\\	2.00
\		Enters constant into Y, Z, and
		T-registers.

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