EC-388 Data Directory
(650-0720) Calculator Faxback Doc. # 45694
You can use the EC-388 to perform standard, memory, percentage and constant
calculations (see "Performing Math Calculations" below), as well as time
calculations (see "Performing Time Calculations" below).
Basic Calculator Tips
Press ON/AC to clear the display for the next calculation.
If you make a mistake before pressing an operator key (+, -, x, /), press
Z/CE to clear the last entry.
Note: If you make a mistake after pressing an operator key, you must press
ON/AC (to clear the display) then start again.
E (error) appears if the result of a math calculation is more than 10
digits long, if you try to divide a number by 0 (math calculations only),
or if the result of a time calculation exceeds 99 hours, 59 minutes and 59
seconds. If this happens, press ON/AC to clear the display.
A minus sign (-) appears to the left of the number(s) if the result of a
calculation is negative.
If M appears on the display, that means there is data stored in memory
(see "Memory Calculations" below.).
Performing Math Calculations
To use your EC-388 to perform standard, memory, percentage and constant
calculations, press [+][-] so 0. Appears on the display.
[x][/]
Standard Calculations
To perform a standard calculation (such as addition, subtraction, multi-
plication or division), simply press the keys in the order the calculation
would appear on paper (or as you would use most other calculators).
Memory Calculations
To perform multistep calculations, use the EC-388's memory calculation keys
(F/M-, D/M+, S/MR, A/MC) as follows:
Press F/M- to total a calculation and subtract the total from memory.
Press D/M+ to total a calculation and add the total to memory.
Note: M appears on the display the first time you press F/M- or D/M+.
Press S/MR to recall the value in memory.
Press A/MC to clear the memory. M disappears from the display.
Percent Calculations
Calculate percentages as follows:
To calculate You press: You see:
What is 12% of 150? 150 x 12% 18.
What percentage of 800 is 600? 600 / 800% 75.
What is a 3% markup added to 120? 120 / 3% 123.6
Constant Calculations
The EC-388 lets you calculate constant and exponential values. When multi-
plying, the first value you enter is the constant. When adding, subtract-
ing and dividing, the second value you enter is the constant.
For example (Multiplication): You press You see
5 x 7 = 35 5 x 7 = 35
5 x 9 = 45 9 = 45
5 x 10 = 50 10 = 50
(Division): 100 / 5 = 20. 100 / 5 = 20.
200 / 5 = 40. 200 = 40.
300 / 5 = 60. 300 = 60.
Exponential Calculation:
3 (to the 6th pwr.) = (3 to the 3rd pwr.) to the 2nd pwr.
You press You see
3 x = = x =
or 729.
3 x = = = = =
Performing Time Calculations
Follow these steps to use your EC-388 to add or subtract in hours, minutes
and seconds and perform time calculations.
Note: You must enter a zero (0) before any single-digit hour, minute or
second (enter 5 seconds as 05, for example).
To enter a specific time in a calculation, use the 24-hour time for-
mat. (For example, enter 14 45 15 for 2:45:15 PM).
1. Repeatedly (if necessary) press [+][-] so H M S (hours, minutes and
[x][/]
seconds) and 00-00-00 appear on the display. The first 0 on the left
flashes.
2. Enter the combination of hours, minutes and seconds (such as 12 25 10)
you want to add to or subtract from, then press the desired operator key
(+ or -). 00-00-00 appears.
3. Enter the hours, minutes and seconds you want to add or subtract (such
as 02 25 10), then press =. The solution for your calculation appears
on the display.
See "Example Time Calculations" below for other examples of time calcula-
tions you can perform on the EC-388.
Example Time Calculations
3 hours, 12 minutes, 23 seconds +
5 hours, 1 minute, 49 seconds =
8 hours, 14 minutes, 12 seconds.
You Press: You See:
03 12 23 + 05 01 49 = 8-14-12
11:26:18 PM -
3 hours, 15 minutes
8:11:18 PM
You Press (using the
24 hour time format): You See:
23 26 18 - 03 15 00 = 20-11-18
(EB 12/4/97)
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