Using the DM15L for simple business calculations

 Although the DM15L is an advanced scientific calculator, and the venerable HP12C is still available, it can easily be used for basic business calculations. I guess it's like driving your Ferrari to buy milk around the corner. Just imagine how much fun buying milk is.

So by basic business calculations I mean product margins etc., not financial calculations, I think the HP12C or DM12L is more suited. I have to admit, the HP10Bii Plus is so much more suited to business calculations than both the HP12C and DM15L, but if you can drive around in a Ferrari why bother with a Tata?

In any business, you have to calculate margins (MU), gross profit (GP), VAT, or GST. It's all about percentages. The STO and RCL functions of the DM15L are ideal for storing and recalling these percentages that you use over and over.

Let's setup a hypothetical situation.

The following markups (MU) are used and stored in registers R1 to R9:

R0: 15% VAT (1.15)
R1: 35% (0.65)
R2: 30% (0.70)
R3: 25: (0.75)
R4: 20% (0.80)
R5: 15% (0.85)
R6: 10% (0.90)
R7: 5% (0.95)
R8: 27.5% (0.725)
R9: 22% (0.78)

To store each number in its register is easy:


[1][.][1][5][STO][0]
[.][6][5][STO][1]
[.][7][0][STO][2]
[.][7][5][STO][3]
[.][8][0][STO][4]
[.][8][5][STO][5]
[.][9][0][STO][6]
[.][9][5][STO][7]
[.][7][2][5][STO][8]
[.][7][8][STO][9] 

The above values can also be stored into a small routine/program. This is handy if you use some of the registers for other calculations. Below is a program that will populate the registers with above values:

[f][R↓][g][RTN][g][P/R]
[f][LBL][C]
[1][.][1][5][STO][0]
[.][6][5][STO][1]
[.][7][0][STO][2]
[.][7][5][STO][3]
[.][8][0][STO][4]
[.][8][5][STO][5]
[.][9][0][STO][6]
[.][9][5][STO][7]
[.][7][2][5][STO][8]
[.][7][8][STO][9]
[g][RTN][g][P/R] 

To run the program press [f][[c] and all your values will be stored from register R0 to R9.

Most distributors have various suppliers, each providing a price list in different ways. for instance, some suppliers/wholesalers provide a single wholesale price for their items, others provide the RSP or recommended selling price, after which you deduct your negotiated discount and add you markup (MU).

So lets see how the final selling prices are calculated.

The first example is from a supplier with flat wholesale price and you only have to add your markup and VAT or GST.

RSP: $150.00
Markup: 35%
VAT: 15%

Algebraically:

[1][5][0][/][.][6][5][x][1][.][1][5][=] $265.38 (13 keystrokes)

RPN:

[1][5][0][RCL][1][/][RCL][0][X] (9 keystrokes)

As you can see, that is 4 keystrokes less. What is more, there is less chance to make a mistake since you are not retyping the value for the margin and VAT every time.

Lets look at another sample where your supplier provides you with a recommended selling price (RSP) and you add your own markup.

RSP: $150.00
Discount: 10%
Markup: 25%

Algebraically:

[1][5][0][x][.][9][/][.][7][5][x][1][.][1][5][=] (16 keystrokes)

RPN:

[1][5][0][RCL][6][X][RCL][3][/][RCL][0][X] (12 keystrokes)

The fact that you don't have to retype values reduces the risk of errors. Just remember which value is stored in which register. At least when you RCL a value you see it in the X register. Using memory registers is really helpful especially if you have to store larger values, i.e. 0.1538. The more numbers the higher the risk of errors.