Posted by **Jane** on Tuesday, May 12, 2009 at 2:59pm.

Is there a formula to sum the digits between two numbers?

eg. 1 to 20 = 1+2+3+4+5+6+7+8+9+1+0+1+1+1+2+1+3+1+4+1+5+1+6+1+7+1+8+1+9+2+0 = ??

I am looking for the numbers 1 to 2008 so I really need a formula!

Please help, thank you.

Jane

- math -
**drwls**, Tuesday, May 12, 2009 at 3:40pm
There must be such a formula, but it will depend upon how many digits are in the number, and what the initial digits are.

From n = 0 to 9, if n is the largest number, the sum of digits is

n(n+1)/2

From n = 10 to 19, in n is the largest number and you include the sum for digits for 1 though 9, the sum is

45 + (n-9) + (n-10)(n-9)/2

For n = 20 to 29, the sum is

55 + 2(n-19) + (n-20)(n-19)/2

And it keeps getting messier.

## Answer this Question

## Related Questions

- math - What two numbers between 40 and 50 that have a greatest common factor of ...
- math - Ayan created these clues to discribe her numbers.She used each of the 10 ...
- math - You have 2 digits, 2 numbers, reverse digits and 54 if the difference and...
- Math - 1.(A)(i)Show that 2+4+6+8+..+2n=n(n+1). (ii)Find the sum of the first 200...
- Algebra - Need help plz. Don't really get this "reversing the digits" What is ...
- Math - Mathematicians have been searching for a formula that yields prime ...
- math - While adding ten two-digit numbers the digits of one of the numbers were ...
- math URGENT!!!! - i have a list of 5 different numbers. the sum of 2 of the ...
- 5th grade - To numbers between 40 and 50 have a grestest common factor of 7. The...
- Number Sentence - In a 4-digit number, the two greatest place-value digits are 2...

More Related Questions