# Why 10?

1. Mar 30, 2004

### steersman

Why is 10 a base number? Why not 4? Is it because we can count to 10 on our fingers? This sounds like a stupid question I know but it's been bugging me.

2. Mar 30, 2004

Nobody knows the exact answer (probably because there is no exact answer), but that's probably about as good an answer as you'll get. It just kinda worked out that way.

3. Mar 30, 2004

### Hurkyl

Staff Emeritus
10 isn't the only one ever used; IIRC the Babylonians did everything base 60. 10 just happened to "win"

4. Mar 30, 2004

I can barely keep track of ten numbers, much less sixty. Multiplication would be absolute hell.

5. Mar 30, 2004

### Hurkyl

Staff Emeritus
otoh there are a lot more 1-digit numbers!

6. Mar 30, 2004

Those are usually the ones that give me trouble...

7. Mar 31, 2004

### ahrkron

Staff Emeritus
I think the mayans used base 20.

Anyway, there are no "base numbers". Any number greater than 1 can be used as a base for a positional system.

And, no matter what number you choose for your base, the representation of that number in that base will be "10" (for instance, 2 in binary is "10"; 3 in base 3 is "10", etc).

8. Mar 31, 2004

### HallsofIvy

Staff Emeritus
The Tlingit people who lived along the Pacific coast of North America (Washington State and British Columbia) used sort of a "base 8" (there numeration system wasn't, strictly speaking, a "base" system) because they counted on the spaces between their fingers!
(As in- place index finger of right hand between thumb and index finger of left, say "1", place index finger of right hand between index and middle finger of left say "2", etc.)

9. Mar 31, 2004

Staff Emeritus
The classic Greek astronomers had a neat system. They used the Babylonian base 60 but expressed the digits in their own traditional alphabetic system - &alpha; = 1, &beta; = 2, and so on with specific combinations for digits above 10. You could probably simulate it by using Roman numerals for base 60 digits, from I to LIX plus zero.

10. Apr 14, 2004

### moshek

Not a stupid question at all.
becase we have 10 fingers.

11. Apr 14, 2004

### Njorl

The question really should be "Why ten?" not "Why 10?".

Think about it. No matter what base we used, it would still be "10".

Njorl

12. Apr 14, 2004

Staff Emeritus
LOL! So true! So the alien with three fingers would say "I have 10 fingers too. 1+1 = 2 and 2+1 = 10."

13. Apr 17, 2004

### toloXXX

Base 10 is for our daily computation...
You dont need to take such a "base" to heart. Modern computers use base 2(-8-16) to represent all the stuff. If you like, you can also define yourself base 3,4,5,6,7 etc. It is not a matter of choice but a matter of which you have to deal with standard and common rules.

14. Apr 17, 2004

### JJ

I wonder if the numbers of fingers on a primitive organism determines its future intelligence.

15. Apr 17, 2004

### Dayle Record

I had a math teacher in seventh grade, she was from nah awlens, in case you are having trouble with that, it is vernacular for New Orleans. She had a great accent, and described 12 as the queen of the numbahs, because it was divisible by so many primes, and we spent a couple of days discussing bases, and how it would have been much better if we had 12 fingers, so we could have used base 12. All in this thick accent. She was a hoot, in her Lady Bird Johnson hairdo, and pastel suits, she was at least 70 years old then.

16. Apr 20, 2004