HP HP12C hp 12c_user's guide_English_E_HDPMBF12E44.pdf - Page 177

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+ 5§ 4+ 3§ 13.00 65.00 69.00 207.00 Intermediate result of (6+7). Intermediate result of 5 (6+7). Intermediate result of [4 + 5(6 + 7)]. 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 2\\ \ Display 2.00 Enters constant into Y, Z, and T-registers. File name: hp 12c_user's guide_English_HDPMBF12E44 Printered Date: 2005/7/29 Page: 177 of 209 Dimension: 14.8 cm x 21 cm