In the second post on Cistercian Numbers, I covered drawing the Cistercian numeral five using ucblogo (Berkeley Logo). Six through nine was left as a future exercise since the numeral for six is a new primitive:

In this post, we’ll cover drawing the numerals six through nine which will round out the single digits.

The numeral for six is relatively straightforward, with the only wrinkle being the PU and PD commands. These are used to leave a horizontal gap between the two vertical lines:

We return to using primitive turtle drawing commands to create the numeral six:

TO Draw.6
  FD 120
  RT 90
  PU
  FD 40
  PD
  RT 90
  FD 40
END

The numerals for seven, eight, and nine will be compound shapes (similar to the numeral for five). The numeral for six will be the base shape we build up from. The numerals for one and two will then be added to it to produce the final numeral.

The numeral for seven can be drawn using the numeral for six plus the numeral for one:

TO Draw.7
  Save.Turtle
  Draw.6
  Restore.Turtle
  Draw.1
END

The numeral for eight can be drawn using the numeral for six plus the numeral for two:

TO Draw.8
  Save.Turtle
  Draw.6
  Restore.Turtle
  Draw.2
END

Finally, the numeral for nine can be drawn using the numeral for six plus the numeral for two plus the numeral for one:

TO Draw.9
  Save.Turtle
  Draw.6
  Restore.Turtle
  Draw.2
  Restore.Turtle
  Draw.1
END

This brings us to another nice break point. The next step will be thinking in terms of the ten’s place numerals for drawing the numbers 10 through 99. As you can see, these are mirrored on the vertical axis from their equivalent one’s place numerals:

In the next post, we’ll tackle an approach to drawing the numerals for ten, twenty, thirty, and forty.