What's pi in Arabic?

Day 12
Fri 29th
Start: Nouakchott, Mauritania
Mid: Nouakchott, Mauritania
End: Somewhere in Southern Mauritania, before Kiffa [16 30 N 11 23 W]

The car ride from Nouakchott to Ayoun el-Atrous on the southern side of Mauritania became my longest car ride to date. 21 hours in the same car. However, we stopped for the night on the side of the rode at some police intersection.

The car I was in had three people up front (including the driver), four plus baby in the middle, and five in the back. Crowded. At the first stop after beginning I bought a bottle of water and noticed that the different elements that were in the mineral water were listed twice: once in english and the other in arabic. I knew I couldn’t figure out the arabic letters, since the words can be translated – but you can’t translate numbers unless you have a different base system (The Wollof tribe in The Gambia uses a mix of base ten and five). For ten minutes I was rolling the water bottle back and forth trying to figure out the arabic numbers. It’s just all pattern recognition. You have a square here, and a square where a seven should be – ah, square is seven – etc.

After a while I asked if anyone had a pen. No one did but someone had a permanent marker in his pocket (!). Even better! Writing directly on the bottle itself I wrote down what I thought was 0-9 in arabic to the amusement of everybody parallel and behind me watching. They started laughing when I got to 3, not so much because I screwed up but because they finally understood what I been doing for the past ten minutes, rolling the bottle back and forth and cross referecing two parts of the bottle. Only made two small mistakes.

ARABIC NUMBERS



Another thing that interested me was the I knew the words were written right to left, but from the water bottle to numbers were written right to left. For instance, 15 would be \ o where I thought it would be o \. This was confirmed a few days later when I on the way into Mali the owner of the truck was Ghanian and therefore spoke English. He demonstrated to me on the road in sand that if they want to write something like

“I am going” in Arabic, it would look like [in English] “gniog ma I” and not “going am I” as I thought. It’s literally read and pronounced right to left. However, if you want to write “I am 25 years old” you would write it as “dlo sraey 25 ma I”. The numbers are written right-to-left, opposite the way you write it! In English it would be like to say “I have 123 paperclips” you would write “I have 321 paperclips” but SAY “I have 123 paperclips.”

In the Wollof tribe in The Gambia, they use base 5 but write it as base 10. ‘68’ is said “five one ten five three”. A few months back Erik and I figured out how they could multiply and divide by five so fast. I highly doubt they do it this way but it “makes sense”

Base 10:
Multiple by 10: add a zero [12 becomes 120]
Divide by 10 (if multiple of 10): subtract a zero [120 becomes 12]

Base 5: same thing
Example: 85 in base five is 320. To divide by 5 (in base five) you subtract a zero so it becomes 32. That number, 32, is the base five representation of 17, which IS 85 divided by 5.

We multiple and divide by ten so easily since it’s what base we are using and we don’t consciously know of the deep mathematics that go into it. I guess the same is true for base 5 in The Gambia.

I practiced learning the Arabic numbers by writing on the water bottle the first 50 digits of pi in Arabic. This is instead of learning the more useful pronunciation of French numbers! For bartering, I use a calculator if they are speaking French. Now if they speak Arabic I can just write the numbers down! In other words, completely useless.