# Senary Base Conversion Tool

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## Bases Greater than 10

Decimal (Base 10) uses 10 digits (0,1,2,3,4,5,6,7,8,9), so what happens when you need more than 10 digits?

### Undecimal (Base 11)

Undecimal (Base 11) needs one more digit than Decimal, so "A" is used, like this:

 Decimal: Undecimal: 0 1 2 3 4 5 6 7 8 9 10 11 12 ... 0 1 2 3 4 5 6 7 8 9 A 10 11 ...

### Duodecimal (Base 12)

Duodecimal (Base 12) needs two more digits than Decimal, so "A" and "B" are used:

 Decimal: Duodecimal: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 ... 0 1 2 3 4 5 6 7 8 9 A B 10 11 ...

Because there are more than 10 digits, hexadecimal is written using letters as well, like this:

 Decimal: Hexadecimal: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 ... 0 1 2 3 4 5 6 7 8 9 A B C D E F 10 11 ...

### Vigesimal (Base 20)

With vigesimal, the convention is that I is not used because it looks like 1, so J=18 and K=19, as in this table:

 Decimal: Vigesimal: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 ... 0 1 2 3 4 5 6 7 8 9 A B C D E F G H J K 10 ...

### Letters (Base 26)

With "Base 26", you use the letters of the alphabet (not 0 to 9).

Some people start with A=0, B=1, etc. But it seems more natural to use A=1, B=2, etc, as everyone thinks that A is the first letter, B is the second, and so on.

So I use the A=1, B=2, convention, and I use "Z" for Zero! Like this:

 Decimal: Base 26: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 ... Z A B C D E F G H I J K L M N O P Q R S T U V W X Y AZ AA ...

It is fun to use Base 26, type your name in, and see what number you are!

Also, try putting in decimal values after the ".", for example 0.1 produces "BOOO..."