# math

posted by .

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!

Jane

• math -

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.

## Similar Questions

1. ### math

You have 2 digits, 2 numbers, reverse digits and 54 if the difference and the sum of all is 10 I'm not clear what you're asking, could you clarify what the conditions are for us please?
2. ### Algebra

Need help plz. Don't really get this "reversing the digits" What is this really called in math language?
3. ### math

Make the largest and smallest numbers you can find using the digits: 4,1,7,8,5 and 2. Find their difference and sum. 1. I do not know if I have to use all the digits. 2. If I do not need to use all of the digits won't there be a lot …
4. ### math

Ayan created these clues to discribe her numbers.She used each of the 10 digits 0to 9 once to make the two numbers. It is between 52000 and 2000. there is a 2 in the tenth place. the sum of the digits is 23
5. ### math

What two numbers between 40 and 50 that have a greatest common factor of 7, the digits of one number is the sum of 6, the digits of the other number is the sum of 13, what are the two numbers?
6. ### Math

1.(A)(i)Show that 2+4+6+8+..+2n=n(n+1). (ii)Find the sum of the first 200 even numbers. (iii)Find the sum of the first 200 odd numbers. (B)(i)Use the formula at the beginning of the question to find the sum of the first 2n natural …
7. ### math

While adding ten two-digit numbers the digits of one of the numbers were interchanged. As a result the sum of all the ten numbers increased by a value which was four less than that number. Three times the sum of the digits of the original …
8. ### Math

Please help. We have to use these digits to solve the two numbers - 2, 9, 4, 3, 6, 7. The difference between the two numbers is 377. What are the two numbers?
9. ### math

What is the formula and the answer of; Two numbers are in the ratio of 4:7 if the difference between the two number is 48 find the sum of two numbers.
10. ### math

Two 5-digit numbers have the same sum of digits: 2. The largest possible difference between two such numbers has the sum of digits: A 1 B 9 C 18 D 27 E 36

More Similar Questions