Hi, I don't know how to solve this problem. Could someone help me?
How many -digit numbers are there, such that the sum of the digits is divisible by ?
Write your question accurately !! How many what? 4-digit, 5-digit, 6-digit numbers? And is divisible by what number?
Sorry, I meant to write how many 10 digit numbers are there, such of the digits is divisible by 5? The digits can be repeated.
Do you want the SUM of the 10-digit number to be divisible by 5? Example:1234567890=45 which is divisible by 5.
This is an arithmetic sequence as follows:
N/2 * [2*1000000004 + 5*(N - 1)] =9900000002700000000, solve for N
N =1,800,000,000 - 10-digit numbers that are divisible by 5.