I must say, I too was captivated by this thread from your very first sentence.
My theory (from an American perspective) is that France and the whole world in general have an intuitive understanding of 69. After that, French culture and behaviors spiral off into the unrecognizeable. 
Both french and english has vigesimal numbering system ( that’s base 20 ). Now that we’re using arabic number we’re all back to decimal system but some of the name have stuck. Their are name for number in decimal system in french but they are not in use very much
…
70 :septante
80 : octante
90 : nonante
…
Here’s a very good book which goes through a good deal of numbering system :
Mathematics, from the birth of number
by
Jan Gullberg
This book is also a very good math revision for those of us who have left the field for a while and want to get back in the game 
This is not true for Sweden and Norway. Danish can be quite hard to understand for me (swedish) when they speak fast. To add to this their numbering system makes it impossible to know how much to pay in shops if you can’t see it in digits. I usally just hand them a lump of money and hope they are honest people. (Stupid me…)
In Sweden the numbering system changes at 12
11 - elva
12 - tolv
13 - tretton
14 - fjorton
-ton corresponds to the english -teen
Actually, the norwegians sometimes switch around units and tens
between 21 and 99 so that, as an example, 24 becomes four and
twenty.
Yeah, that was one thing that bugged me about German! When they wanted to go to page 124, it would be “one hundred four and twenty.” It’s SOOO annoying.
I’m pretty sure that the decimal numbers already mentioned numerous times “setante…” in French are used almost everywhere in the spoken language. I’m a French major at University, and one of the classes I had last semester was an advanced oral class, and we were discouraged from saying “soixante-dix, etc…”
Spanish has also messed me up - sometimes it’s “vientiseis” where you can contract the “twenty and six”… and sometimes it’s “trenta y seis” where you have to spell out the “thirty and six” (I’ll apologize now for my aweful Spanish spelling, but it was my fourth foreign language and I was only interested in learning to speak it)
Your French teacher DISCOURAGED the use of “soixante-dix” etc?!?! Then he wasn’t teaching French, he was teaching a dialect. I grew up in Quebec, and my family still lives there, and I only first heard the other terms about 2 years ago from a Swiss chef where I worked. And the French chef continually corrected him.
I begin to see the frustration of the “dying French language” POV of some sovereignists when I hear things like this. Sure, SOME people might use it, but it isn’t the language, no matter how common it is is some regions. And French actually has an Institution determining what is and isn’t the language. Unlless your class focused on regionalisms and slang (which is totally acceptable, and in which case I appoligise for this rant), then your prof was not teaching you what you were there to learn.
Of course, thats just my humble opinion, and sorry for slamming you, but still…discouraged!!!
Well, nice discussion … held by english speaking people. 
Time for a BELGIAN to fix some things. 
I know, waaaaay to late (twelve years, :eek: :smack:) but life sucks at this time and I can really think of nothing better to waste it on.
So here goes:
First of all, why do I think I’m in title to bud in? I’m a bi-(quadrupal actualy)-lingual Belgian
Belgium is bi-lingual (situation kinda like in Canada), with people speaking dutch in the north (Flanders) and french (Wallonia) in the south. The flemish is the same language as the dutch in the netherlands, but with a distinct difference in pronounciation and use of words, dialects, figures of speatch, same difference as British english and American English. No, the difference is even greater. You REALLY can distinct a Flemish from a Dutchman as you would a Brit and an American.
Btw, in dutch we use the same numbering as the Germans do. From twenty-one and so on the Tens come after the Ones, five-and-twenty (25), Flemish hundred-AND-one as to dutch hundred-one (101)
octante: this is NEVER used at all in Belgian Wallonia. They use
70 = septante (not setante, the “p” is not silent)
80 = huitante
90 = nonante (not neufante)
“…DISCOURAGED …”: indeed wrong! If you use these three numbers in France, you will puzzle people They might even be insulted as they do not really like the wallonians, nor theyr dialect.
70 = soixante-dix
80 = quatre-vingt
90 = quatre-vingt-dix
As a purist I find it very disturbing that they (the government) changed the teaching of French as a second language to Wallonian over the years. Not only did they change the numbering (now septante instead of soixante-dix) they also got wrid (or rid or whatever) of the term vous, votre, meaning you, your plural OR first contact/polite. They just use tu,toi, which you only use among friends or family. Use tu or toi on a holiday and you will get no service or even worse, some extra service :eek:
That’s it for now.
Curous if ANYONE will repond to or even READ this after so long :rolleyes:
Because it was base-12. Which is why there’s also a special term for 12x12.
Which is…? Or is it unpronounceable? 
Never mind – I remembered. Eww, yucky.
Once they got to 69, the French lost all interest in having a rational system of counting.
Yeah, but that’s just gross.
I’m surprised that in the 12 years of this thread no one has mentioned that Basque uses vigesimal (base-20) numbers. It seems likely that Celtic picked up their system from proto-Basque.
Among other vigesimal languages is Burushaski, an isolated language of Pakistan with which Basque is sometimes linked. (This connection seems far-fetched given the huge distance from Spain to Pakistan, but is supported by cognates, regular sound changes, and the idea that both are vestiges of the language of the earliest farmers of the Near East.)
Did it depend on how many blackbirds they could bake in a pie?
Of the Scandinavian languages, only Danish does that bugfuck crazy thing where
50 = “half third”
60 = “third”
70 = “half fourth”
80 = “fourth”
90 = “half fifth”
The two (unspoken!) ideas behind this being that a) “half” doesn’t mean “50%,” but rather “minus 0.5”; and b) everything is to be multiplied by twenty.
50 = “half third” (2.5 x 20)
60 = “third” (3 x 20)
70 = “half fourth” (3.5 x 20)
80 = “fourth” (4 x 20)
90 = “half fifth” (4.5 x 20)
As you can imagine, this tentacled pit of Lovecraftian horror that is Danish numbering has led many an nerve-frayed Swede to flee back across the strait in horror and revulsion, and spend the rest of their cursed existence mumbling in a rocking chair about “the halves,” “the twenties” and the cosmic goat of a thousand young. “Why they ever built that bridge, I’ll never know! Fools, I say! Fools! They know not what they’ve wrought…!”
My Danish friend told me it was because Swedes were returning to their country so drunk that sea-sickness was a major problem on the ferries.
There are all kinds of oddities:
2…a couple
2…a pair
2…a brace
6… half a dozen
12…a dozen
13…a baker’s dozen
20…a score
144…a gross (12 dozen)
At school I had to learn my tables up to 16 because there are 16 ounces in a pound weight. 12 was even more important because there are 12 inches in a foot and were 12 pennies in a shilling.
Then there is the betting man’s jargon - £20 is a Score, £25 a Pony, £100 a Ton, £500 a Monkey, and £1000 a Grand.
Because up until the tenth/eleventh century or so, when the Abbassid califate introduced base 10 counting, “arab” numbers and the zero ; people counted in base 12.
Don’t ask me why OR how, I already have a hard time wrapping my mind around doing *any *kind of math without 0 :). I guess they counted on their fingers, using the closed fist as one additional number ?
The thing about the French system is that you can’t do what you would normally do with strange words. You can’t just treat soixante-dix as a funny way of saying “seventy.” Because, when you go above that, you don’t say soixante-dix(et)un, but soixant-onze. You say sixty-eleven, followed by sixty-twelve, sixty-thirteen, etc. You either have to treat all those numbers as oddballs (at least up until soixante-dix-sept, “sixty-seventeen”), or you treat 60 as different, having an extra 10 numbers that are for some reason written with a “7” in front of them.
While you can see quatre-vingt as just being a funny way to say “80,” without a huit (8) in it anywhere, but you run into the same problem with ninety. It’s eighty-eleven, eighty-twelve, eighty-thirteen, etc.
So for two multiples of ten, you have to switch to base-20. That’s what seems so weird.
The knuckles in the fingers of a hand, with the thumb in contact with the current knuckle: Duodecimal - Wikipedia
One hand counts the base using the knuckles of the non-thumb* fingers while the other hand uses all fingers to count to 60.