The number format

Let's look again at the format of our numbers. It's crucial that you understand why they look like they do.

The complete Johnny.Decimal number

Just as a reminder, every Johnny.Decimal number looks like this.

12.34   12.35    
13.03   13.04
21.01   21.02
22.38   22.39
23.21   23.22
23.23   23.24
31.70   31.71
32.55   32.56

In words, we have any two digits, followed by a decimal point, followed by two more digits.

Johnny.Decimal is all about grouping similar things together, so let's start to do that.

All the 12 numbers
        12.34   12.35

All the 13 numbers
        13.03   13.04

All the 21 numbers
        21.01   21.02

All the 22 numbers
        22.38   22.39

All the 23 numbers
        23.21   23.22
        23.23   23.24

All the 31 numbers
        31.70   31.71

All the 32 numbers
        32.55   32.56

That's starting to look more like something organised and a bit less like a bunch of random numbers. Let's take it one step further.

All the 10-19 numbers
   All the 12 numbers
           12.34   12.35
   All the 13 numbers
           13.03   13.04

All the 20-29 numbers
   All the 21 numbers
           21.01   21.02
   All the 22 numbers
           22.38   22.39
   All the 23 numbers
           23.21   23.22
           23.23   23.24

All the 30-39 numbers
   All the 31 numbers
           31.70   31.71
   All the 32 numbers
           32.55   32.56

Interesting. You can almost imagine this looking like a set of folders; if you didn't care about anything except the 22 numbers, you could just collapse the others like this.

Concepts - The numbers - Folded showing 22.png

This is how we structure the numbers

When we decide to organise something with Johnny.Decimal, we break it up like this:

  • First, we divide everything in our system in to (at most) ten large buckets of stuff. We call those our areas.
  • Then, within each area, we break things up again in to (at most) ten more buckets. We call them categories. Everything related to a particular category is in that bucket.
  • Finally, we assign each individual thing in our system a unique number. We start at 01 and work our way through the numbers.

I'll walk you through doing this yourself later. For now just make sure you understand the concept.

If we write that out without using any numbers, it might look like this. Let's use a really small company as an example.

Folder                                This is a...
--------------------------------------------------
Finance                               AREA
    Tax returns                       CATEGORY
    Payroll                           CATEGORY
        September ’17 payroll         UNIQUE THING
        October ’17 payroll           UNIQUE THING
    Bookkeeping                       CATEGORY

Administration                        AREA
    Company registration              CATEGORY
    Contracts                         CATEGORY
        Cleaning contract             UNIQUE THING
        Office lease                  UNIQUE THING
    Staffing                          CATEGORY

Marketing                             AREA
    ...etc.                           ...etc.

All we really do with Johnny.Decimal—and if at this point you’ve realised this and are thinking, “hang on, all he’s done is put numbers in front of things” well then you’re not far wrong—is put numbers in front of things.

But that is everything. It transforms the way you think about and use everything. Trust me.

Let's put numbers in front of the system we just built above.

Folder                                This is a...
--------------------------------------------------
10-19 Finance                         AREA
    11 Tax returns                    CATEGORY
    12 Payroll                        CATEGORY
        12.01 September ’17 payroll   UNIQUE THING
        12.02 October ’17 payroll     UNIQUE THING
    13 Bookkeeping                    CATEGORY

20-29 Administration                  AREA
    21 Company registration           CATEGORY
    22 Contracts                      CATEGORY
        22.01 Cleaning contract       UNIQUE THING
        22.02 Office lease            UNIQUE THING
    23 Staffing                       CATEGORY

30-39 Marketing                       AREA
    ...etc.                           ...etc.

What does this achieve? For one, it's removed our dependence on the alphabet. The alphabet is a fine thing but it is a terrible way to sort your files because things move around. Today we have:

Adminstration
Finance
Marketing

...and tomorrow those clowns from the exports department come along and do this:

Administration
Exports         (folder added)
Finance
Marketing

...and Finance isn't the second thing in the list any more. It's moved! Dammit. This sounds like a small thing but it makes it impossible for your brain to learn where something will be.

With Johnny.Decimal, we would end up with:

10-19 Administration
20-29 Finance
30-39 Marketing
40-49 Exports

Because our folders all start with a number, they'll sort in very predictable way. This concept applies throughout the system.

20, 60, 30, 90, whatever

At this point you might be wondering, well, why is Finance all of the numbers from 20-29 and why is Exports 40-49? What do those numbers mean? And the answer is that they mean nothing. They're just numbers. 40 isn't better or worse than 20.

You should be getting it by now

On this page I've talked mostly about the way that we structure our areas and categories, and by now you should have a good high level understanding. You have categories of things, and each category belongs to one and only one area. Areas group categories together.

All of this happens before the decimal. The two digits of the number are the category, and the first digit of the number tells you which area it's in.

What we’ve done here is organise a bunch of ‘stuff’ in to something with structure; we’ve created, essentially, a very simple database.

Now let's move on to what happens after the decimal.