sum of serial numbers on a dollar bill - what's the term?

[newbury]

Sometime in my bored youth (long before the internet) we used to compare dollar bills by summing up all the individual numbers, then summing the individual numbers until we got down to a single digit.
(Sort of a sum of a number using recursion)
So for example:
F40316889P would sum to 4+0+3+1+6+8+8+9=39 and 3+9=11 and 1+1=2

Is there a word for that?

 

[LS Tractor Owner]

To much time on your hands? Just kidding.... You sparked my curiosity.... I could not find a specific name for it.... but hard to describe in order to find....

 

[CobyRupert]

I think your question contains the answers, but the words just don’t fall into the right order.
I think the most concise terms are “sum of the digits” or “digit sum” for the individual steps taken.
I’m not sure what you call it when you repeatedly “digit sum” the previous “digit sum” until you’re only left with 1 digit.

Edit: Hold on! The “digital root” is the result of repeated “digital sum”.
Wikipedia says :

The concept of a decimal digit sum is closely related to, but not the same as, the “digital root”, which is the result of repeatedly applying the digit sum operation until the remaining value is only a single digit. The digital root of any non-zero integer will be a number in the range 1 to 9, whereas the digit sum can take any value. Digit sums and digital roots can be used for quick divisibility tests: a natural number is divisible by 3 or 9 if and only if its digit sum (or digital root) is divisible by 3 or 9, respectively. For divisibility by 9, this test is called the rule of nines and is the basis of the casting out nines technique for checking calculations.

Digital root - Wikipedia

 

[newbury]

I think your question contains the answers, but the words just don稚 fall into the right order.
I think the most concise terms are 都um of the digits or 電igit sum for the individual steps taken.
I知 not sure what you call it when you repeatedly 電igit sum the previous 電igit sum until you?*e only left with 1 digit.

Edit: Hold on! The 電igital root is the result of repeated 電igital sum?
Wikipedia says :

The concept of a decimal digit sum is closely related to, but not the same as, the 電igital root? which is the result of repeatedly applying the digit sum operation until the remaining value is only a single digit. The digital root of any non-zero integer will be a number in the range 1 to 9, whereas the digit sum can take any value. Digit sums and digital roots can be used for quick divisibility tests: a natural number is divisible by 3 or 9 if and only if its digit sum (or digital root) is divisible by 3 or 9, respectively. For divisibility by 9, this test is called the rule of nines and is the basis of the casting out nines technique for checking calculations.

Digital root - Wikipedia

Great!
That's a start.
Thanks!

 

[plowhog]

F40316889P would sum to 4+0+3+1+6+8+8+9=39 and 3+9=11 and 1+1=2

You're saying 3+9=11?

 

[techman]

In computer systems adding every byte of code then looking at the sum (or part of the sum) is a method of verifying the validity of the file. It is called a "checksum". More advanced methods factor values and sum them to provide a more robust check on validity. That is known as "CRC", for cyclic redundancy check.

paul

 

[MossRoad]

You're saying 3+9=11?

New math...

 

[Diggin It]

You're saying 3+9=11?

It's kinda like VT + VA = MS

 

[bcp]

You're saying 3+9=11?

It depends on which value of 3 you use.



Bruce

 

[Diggin It]

Three dollar bills have no value.