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No. 65-423 OWNER’S MANUAL Please read before using this equipment. EC-293 2-Line Pocket Calculator © RadioShacks FEATURES Your RadioShack EC-293 2-Line Pocket Calculator has two power sources, so you can use it almost anywhere. Its built-in solar panel provides power when you expose the calculator to light. When the surrounding light is not bright enough, the supplied internal battery provides the power. The calculator’s features include: Two-Line Display — lets you easily see the memory value on the upper line, and the total calculation and the number you just entered on the lower line. Four-Function Memory — saves important subtotals, and lets you add to and subtract from them. © 1999 Tandy Corporation. All Rights Reserved. RadioShack is a registered trademark used by Tandy Corporation. vffir 2 i +/- Key — changes the sign of the displayed number. Percentage Key — simplifies discount, percentage change, and tax calculations. SHIFT Key — lets you view and total a memory value with a new entry on the same display. Automatic Power-Off — conserves battery power by turning off the calculator if you do not press a key for about 8 minutes. Auto-Comma — the calculator automatically adds commas to numbers over three digits, making it easy to read large numbers. 3 CONTENTS A Quick Look at the EC-293 ... 5 Operation ................................. 6 Correcting Entry Errors ......... 7 Calculation Errors ................. 8 Estimating Calculation Results 9 Using the +/- Key ............... 10 Calculation Examples ..........11 Mixed Calculations ............ 11 Percentage, Add-On, and Discount Calculations............ 12 Constant Calculations ...... 13 Reciprocal Calculation ..... 14 Exponential Calculation .... 14 Memory Calculations........ 15 Using Shift........................... 19 Care ........................................ 21 Resetting the Calculator...... 22 Replacing The Battery ........ 23 Specifications ........................ 28 4 1 ^ A QUICK LOOK AT ^ THE EC-293 Memory Keys. ON/C.CE — press to turn on calculator and clear entries. 00000 000 000 SHIFT press to view second line. AC — clears all calculations. & 5 1 OPERATION Press ON (C.CE) or AC to turn on your calculator. If you do not press a key for about 8 minutes, your calculator automatically turns off. Your EC-293 lets you calculate normal and memory values separately and total them together. When you store or calculate a value in memory, the memory value displays on the upper-line. You can see the total calculation and the number you just entered on the lower line. To total both values, press SHIFT (see “Using Shift” on Page 19). 6 CORRECTING ENTRY ERRORS If you enter an incorrect value, press C.CE (ON) once, then enter the correct value and continue your calculation. To clear the display for a new calculation, press AC so 0. appears, then begin the new calculation. Note: Pressing AC also clears any calculations stored in memory. If you enter an incorrect function key (+, -, x, *), simply press the correct key and continue your calculation. 7 w CALCULATION ERRORS E (error) appears in the lower left corner when: • A calculation result exceeds eight digits to the left of the decimal point. This is an over- _/^n_ flow error (see “Estimating Calculation Results” on Page 9). • A memory calculation result exceeds eight digits to the left of the decimal point. Memory contents remain unchanged. • You try to divide by 0. If E appears, press C.CE once to clear the error, or press AC to clear the display. 8 1 Estimating Calculation Results If you perform an operation that results in an overflow error, you can estimate the correct result (to eight significant digits) by following these steps. 1. Count the number of digits displayed to the left of the decimal point. 2. Remove the decimal point. 3. Add as many zeros to the right of the number as there were digits to the left of the decimal point. 9 For example, if E 1.0142064 appears, the approximate answer is 101,420,640. If E 319.70347 appears, the approximate answer is 31,970,347,000. USING THE +/- KEY Press +/- to change the displayed _/i\ value from positive to negative or from negative to positive. & 10 CALCULATION EXAMPLES Mixed Calculations You Press You See 24 + 24. 1 <0 CO 60. 75 x - 15. 9 = - 135. & 11 w Percentage, Add-On, and Discount Calculations Calculation: 20% of 720 You Press You See 720 x 20 % 144. -(*>)- Calculation: 30% added to 540 -(<*)- You Press You See 540 + 30 % 702. Calculation: 20% reduction of 800 You Press You See 800 - 20 % 640. 12 1 Constant Calculations For multiplication, the first value you enter is the constant. For addition, subtraction, and division, the second value you enter is the constant. You Press You See 5 x 7 = 35. 9 = 45. 10 = 50. 100 ^ 5 = 20. 200 = 40. 300 = 60. 13 Reciprocal Calculation To find the reciprocal of a number, simply enter the...