Spotlight: Casio DF-320TM (updated 6/17/2025)

Spotlight: Casio DF-320TM

Just the Facts

Model: DF-320TM

Company: Casio

Type: Desktop

Number of Digits: 12

Display: 3 lines

Power: Solar plus backup battery, LR 44

Years of Production: My guess is somewhere in the 2000s

Several months ago, I found this calculator at a thrift shop in Montclair, California for a $1.35 (after discount). The DF-320TM is a nice desktop calculator with three lines. The top two lines are used for specific purposes, while the bottom on line has general calculation and results on the third line.

Features

The features of the DF-320 TM include:

* 12 digit display. For those of us working with large numbers, the extra digits are nice.

* Two slide settings that are found on desktop calculators: rounding and the fixed decimal settings. Add mode is available for those who are proficient with adding machines or those who like working with dollars and cents without having to enter the decimal point.

* Cost/Sell/Margin* calculation

* Sales tax and discount

* Exchange rate calculations between two currencies

* An [ H/M/S ] button which allows for hours-minutes-seconds calculation.

* Tracking of grand total every time when the equals key ( [ = ] ) is pressed. The grand total is retrieved by pressing the [ GT ] key.

* Determining change with the [ CHANGE CAL ] button.

(*I made a mistake in calling it Markup.   Gratitude to Christopher Brown for letting me know about the error.)  

All examples have the following setting: 5/4 rounding fixed to 2 decimal places.

Cost/Sell/Markup

The three keys, [ COST ], [ SELL ], and [ MAR ] (MAR for Markup) solve cost-sell-markup problems. Entries are made on the top screen and solving for the third variable occurs automatically.

Example:

1200 [ COST ] 12 [ MAR ]

Display:

COST> 1,200.00

MAR> 12.00%

= 1,363.64 (selling price)

Setting Tax and Exchange Rates

The DF-320TM employs the traditional way to set tax rate and currency exchange rate.

1. Start by pressing and holding [ AC ] and [ % ] until the screen reappears with the SET indicator.

2a. For the tax rate: Press [ TAX+ ], enter the tax rate, then press the [ % ]/

2b. For the currency rate: Press [ C2/EX RATE ]. Symbols such as $, €, £, A, B appear on the top left hand display as such: £ → $. Cycle through the symbols by pressing the [ + ] (↓RATES) key. Type in the rate and press [ % ]. You can view the rates going both ways by pressing the [ - ] key in this mode.

3. Press [ AC ] to return to normal calculator mode.

Example: $1 is converted to € 0.9027

Hold [ AC ] and [ % ] until SET appears. Press [ C2 ]. Press [ + ] until $ → € appears.

Enter 0.9027 and press [ AC ]. In this setting $ belongs to C1 and € belongs to C2.

$15 converted to Euros: 15 [ C2 ]. Display:

$ 15

RATE > 0.9027

€ 13.54

€200 to U.S. Dollars: 200 [ C1 ]. Display:

€ 200

RATE > 1.10778774786

$ 221.56

The three line display in used in a similar structure with tax calculations.

Change Calculation

The [ CHANGE CAL ] is used for change calculations, after a calculation is completed with the equals key [ = ]. I discovered this function by accident because the manuals I could find online did not give a thorough description of the function.

< calculation > [ = ] amount [ CHANGE CAL ]

Example 1:

Three items are priced 13.84, 17.01, and 19.99 are purchased. Assume that sales taxes are included in the price. You gave the cashier 100.

[ AC ] 13.84 [ + ] 17.01 [ + ] 19.99 [ = ]

Display:

GT = 50.84

100 [ CHANGE CAL ]

Display:

PRICE> 50.84

PAYMENT> 100.00

GT = 49.16

(Change: 49.16)

Example 2:

Three items are priced 11.95, 9.95, and 31.85. Sales tax is 9%. You give the cashier 100.

Press [ AC ] and [ % ] until SET appears. [ TAX + ] 9 [ % ]

[ AC ] 11.95 [ + ] 9.95 [ + ] 31. 85 [ = ]

Display:

GT 53.75

[ TAX+ ]

Display:

TAX 4.84

9%

T + GT 58.59

[ = ]

Display:

GT 58.59

100 [ CHANGE CAL ]

Display:

PRICE> 58.59

PAYMENT> 100.00

GT = 41.41

(Change: 41.41)

That is the Casio DF-320 TM in a nutshell. I understand that several calculators with the change calculation are or were sold in Asia, if memory serves me correctly.

Until next time,

Eddie

All original content copyright, © 2011-2024. Edward Shore. Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited. This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.

Review: Casio DE-12E-WE Ergonomic Calculator

Review: Casio DE-12E-WE Ergonomic Calculator

3° Tilt

Quick Facts

Model:  DE-12E-WE

Company:  Casio

Years:  Internationally: 2022 - present, United States: March 2023 - present

Type:  Desktop

Power:  Solar with CR 2025 backup battery

Display:  12 digits

Original Price:  $30.99 US Dollars

Memory Registers:  1

Operating System: Chain

Casio's promotional video (United States):  

https://www.youtube.com/watch?v=-6NlPVBSK7U

Casio released a series of ergonomic desktop calculators:

DE-12E-WE:  $30.99 retail, 12 digits, width of 140 mm (about 5.512 inches)

JE-12E-WE:  $27.99 retail, 12 digits, width of 111 mm (about 4.331 inches)

The features between both calculators are virtually the same, except (1) the arrangement of the keys are different, and (2)  the DE-12E-WE has two extra settings, which we will discuss next.

Features

Decimal Setting Switch:  Add Mode, 0, 1, 2, 3, 4, 5 (DE-12E-WE only)

Rounding Setting Switch:  F (Float), CUT (truncate), 5/4 (regular rounding), UP (round everything up, DE-12E-WE only)

[M/EX] Key:  Memory and Exchange mode toggle.  The mode affects four keys, which text of these keys are in blue. 

Memory Mode (no indicator):

[ M+ ]:   add the number in the display to memory M

[ M- ]:  subtract the number in the display from M

[ MR ]:  recall the value stored in M

[ MC ]:  clear the value stored in M (set M to zero) 

Exchange Mode (EXCH indicator):

[ M+ ] (C1):   currency 1 - base currency;  always set to 1

[ M- ] (C2):  currency 2

[ MR ] (C3):  currency 3

[ MC ] (C4):  currency 4

In exchange mode, currency 1 is the base currency is always set to 1, which the other three currencies are set to the exchange rate relative to C1.  Each of the other three currencies can be set one at time.  Start by with holding the [ AC ] and the [ % ] keys simultaneously.  Keep holding the keys until the display refreshes and a SET indicator appears.   Choose a currency (C2, C3, or C4), enter a rate, then press the [ % ] key to set the currency rate.

We also have the tax functions, which text are in green.

[ TAX- ]:  subtract the tax rate from the number in the display

[ TAX+ ]:  add the tax rate to the number in the display.  Use this key to add sales tax to a purchase.

The tax keys are available in either Memory or Exchange mode.   To set the tax rate:  hold the [ AC ] and [ % ] keys until the display refreshes and a SET indicator appears.   Then press the [ TAX+ ] key, enter the rate, then press the [ % ] key.  

The DE-12E has the square root function, and I am big on the square root function on the desktop calculators.   

The 3° Tilt

Casio markets the 3° tilt to promote ergonomic typing on the desktop calculator.   The tilt on both the DE-12E-WE and JE-12E-WE tilt downwards from the left, which is designed for right-handed users.   The keys themselves are curved to facilitate easier finger movement.  

The titled keyboard is comfortable to use, and I did notice a slight increase in typing speed.   The keys are big, which allows me to type without the worry of pressing a neighboring key or two keys simultaneously by accident.  

I also tried the DE-12E-WE with my left hand, at first the keyboard was intense, but I did feel comfortable.  Being right-hand dominant, I am faster with the right-hand.  I am thinking if this series is a success, perhaps there will be a left-handed version of the calculator.  

Final Thoughts

I like the 3° tilt and the clean, professional look of the 12E-WE.  I like how the keys are designed for fast typing.  

I can see the currency exchange mode used for conversions of a common measure, such as feet-meters-miles-kilometers or liters-quarts-cups-gallons.  

Because I tend to use the memory keys in practice, I wish the those keys on the DE-12E-WE were the same size as the number keys, but it does not take away from the comfort and use of this calculator.  

With ergonomics being promoted in the office and financial settings, I expect this series to sell well, which will lead to more ergonomic-friendly calculators in the future.  The 12E-WE is worth checking out if you want a desktop calculator with a lot of features, ergonomics is important, or you are type fast on a desktop calculator.

Eddie 

All original content copyright, © 2011-2023.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Review: Casio MC-12M Shop Calculator

Review:  Casio  MC-12M Shop Calculator

Just The Facts:

Model:  MC-12M Shop Calculator 

Company: Casio

Type:  Desktop 

Display:  12 digits

Battery:  Solar and Battery (AA battery backup)

Logic: Chain

Memory:  Two:  M and Grand Total 

Double Zero Key

Web Site:  https://www.casio-intl.com/asia/en/calc/products/MC-12M/

I purchased this calculator several months ago at a WalMart for about $11.50. 

Features:

Cost/Sell/Margin Calculation

Change Function

Square Root

The display is set an angle so it is tilted towards the user.  I find the keyboard a pleasure to use.  My hands may be a little big, but with the right size of hands you can speed type on the MC-12M.   The keys are fast and responsive.  

Memory

There are two memories within the MC-12M:  the independent memory M and the Grand Total key.  

The independent memory works with the usual memory plus (M+) and memory minus (M-) keys.   The recall (MR) and clear memory (MC) keys are separate keys on the MC-12M.  

The grand total memory is activated every time you press the equals [ = ] key.  On the MC-12M, the grand total memory is automatic.   The grand total memory is cleared when either [AC/ON] is pressed or the calculator is turned off.  

The Change Feature

The big selling feature of the MC-12M Shop Calculator is the [CHANGE] button.   You enter an amount and press [CHANGE], like you were handed cash in a transaction.   When it is pressed, it compares the amount entered against the amount in the grand total memory registered.  The independent memory is not used in the change feature.  

Example:

You have a $100 bill (C-note) and purchase the following:

1 SD card for $19.95

1 desktop calculator for $11.49  ;)

3 reams of paper for $5.00 each (on sale)

15 pens at $0.49 each

2 USB drives, 32GB for $10.60 each

Sales Tax: 9%

Keystrokes:

[AC/ON]

19.95 [ = ]

11.49 [ = ]

3 [ × ] 5 [ = ]

15 [ × ] .49 [ = ]

2 [ × ] 10.60 [ = ]

[ GRAND TOTAL ]     (Display: 74.99)

[ × ] 9 [ % ] [ = ]

[ GRAND TOTAL ]     (Display/Total Invoice: 81.7391   [$81.74]  )

100 [ CHANGE ]   (Change: 18.2609  [$18.26] )

Percent Change

You can calculate percent change with the use of the minus and percent keys.

%CHG Keystrokes:   new [ - ] old [ % ]

Calculate the percent change from 14.75 to 19.85?

19.85 [ - ] 14.75 [ % ] 

Percent Change:  34.5762711864   (34.5762711864%)

Wishes and Verdict

There are two things the MC-12M Shop Calculator have:

Fix Decimal Selector:  This would be great for the shop because most currency calculations work with 2 decimal places.   My selection of choices would be 0, 1, 2, 3, 4, 6.

I would also like to see the Add Mode added. 

Since this is a shop calculator, I can imagine people using this calculator to calculator areas and volumes, so a π key would be nice.  

π ≈ 3.1415926535

This calculator is nice to operate and hold and yes, I like the square root (which should be present on more desktop calculators).   Worth a look.

Eddie

All original content copyright, © 2011-2020.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Retro Review: Radio Shack EC-2024

Retro Review:  Radio Shack EC-2024

Quick Facts

Company:  Radio Shack
Years in Production: Around 1994
Original Price: $24.99
Battery:  Solar with Battery backup  (RS 389A)
Type:  Desktop- Fold-able
Number of Digits: 10

Initial cost and year came from the CALCUSUEM web site:  http://www.calcuseum.com/SCRAPBOOK/BONUS/46394/1.htm  (retrieved August 4, 2019)

I paid $3 for this at a swap meet. 

Keyboard

The some of the keys are larger than the others.  The plus key has an L-shape, while the minus key is large, and the equals key, labeled the "ANSWER BAR".

The keyboard is alright.  If you type at a reasonable pace, the keys are responsive.  If you are speed typist, prepare to be disappointed. 

The EC-2024 works best when the calculator is under full light. 

Settings 

There are two settings switches:

Rounding:  always round up, always round down, or 5/4 (use the general rounding rules)

Decimal Setting:  float, 0 decimal places, 2 decimal places, 3 decimal places, or add mode.  In add mode, every number that is added or subtracted is automatically divided by 100.  This allows for rapid entry of dollars and cents without having to enter the decimal point. 

The Δ% Key

How the percent key [ Δ% ] depends on what arithmetic operation is used with it.

x [ + ] y [ Δ%] returns (x + y)/y * 100%

Example:  250 [ + ] 300 [ Δ% ] returns 183.3333333

x [ - ] y [ Δ% ] returns (x - y)/y * 100%

Example:  250 [ - ] 300 [ Δ% ] returns -16.66666666

(This is the true percent change function, x is new, y is old)

x [ * ] y [ Δ% ] returns x + x * y / 100

Example:  250 [ * ] 300 [ Δ% ] returns 1000

x [ ÷ ] y [ Δ% ] returns x/(1 - y/100)

Example:  250 [ ÷ ] 300 [ Δ% ] returns -125

Verdict

It's a nice calculator and will fulfill the basic needs.  The keyboard is nice and fold-able.  If you get it, spending a few dollars (like no more than $5) is good. 

Eddie

All original content copyright, © 2011-2019.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.

Review: Casio DJ-120D

Review:  Casio DJ-120D

Type:  Desktop
Number of Digits: 12
Power:  Solar with Battery Backup (LR44)
Operating Mode: Chain

Large Size Calculator

This calculator is huge.  The keyboard is nice and large.  The keys are large, that you can easily rapidly type calculations.  The screen is also large, making the numbers the screen easy to read. 

The keyboard has a double zero ( [00] ) and a a triple zero ( [000] ) key, you can enter large numbers rapidly. 

Display Options

There are many display options, primarily by two switches.  One switch sets the number of decimal points (0 through 4 and add mode).  The other switch determines how numbers are rounded (float (not at all), cut (truncated), up (round up), and 5/4 (regular rounding)). 

You can set additional displays modes, such as comma or decimal point for fractional marks using the [ AC ]/[DISP] key and scrolling through the options.  You actually make two settings.  Those two settings get toggled with the [DISP] key in regular calculator mode. 

Add Mode

Add mode allows numbers to be added and subtracted in "dollars and cents" (divided by 100).  The automatic division by 100 is not affected by multiplication and division.  Add Mode is activated when the rounding mode is set to either cut, up, or 5/4. 

Reviewing and Editing Calculations

The DJ-120D has a 150 step memory.  All the arithmetic calculations are stored in each step.  Historical calculations are finalized by either pressing the equals sign [ = ] or the percent sign [ % ].  Calculations can be reviewed by using the arrow keys, the [GO TO] key, or the [AUTO REVIEW] key. 

When you are using the review feature, the display may not be intuitive.  For the arithmetic and percent sign, the function is read on the top of screen.  When you conclude a calculation, the display will show the equals sign on the left side of the screen.  This takes getting used to. 

Example:  Reviewing the Calculations

1120 [+ ]
365 [ - ]
630 [ = ]  

The result is 855.

Review of the calculations:

01  REV  1120 +
02  REV  365 -
03  REV  =  630
04  REV  ANS 855

Note how the equals sign is on the left, not on the right.  It may be confusing to read at first.  Also, square root operations affects only the number in history, the square root function is not recorded as a step. 

While editing operations, you can correct steps.  For example, I change the first step to 1210 +. 

[GO TO] 1 [GO TO]
[CORRECT] 1210 [ + ] [CORRECT]

Reviewing the steps:

01  REV  1210 +
02  REV  365 -
03  REV  =  630
04  REV  ANS 945

The Grand Total Feature

The DJ-120D has a Grand Total feature.  This accumulates every calculation that is completed by pressing the equals key.  You can recall the grand total by pressing [ GT ].   The grand total is a separate memory register.

Example:

46 [ + ] 43 [ = ]  (89)
100 [ - ] 57 [ = ]  (43)
5 [ * ] 9 [ = ]  (45)
[GT] returns 177.  (89 + 43+ 45)

The all clear key [AC] (also ON) clears both the grand total and history.

The Markup Key

The markup key [MU] performs the operation x/(1 - p%). 

Verdict

I love the large keyboard and the display.  I would recommend this calculator for students who are learning math (the review function makes it useful to review math calculations), and office professionals.

Eddie


All original content copyright, © 2011-2019.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.  Please contact the author if you have questions.