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# Find M-th number whose repeated sum of digits of a number is N in C++

In this problem, we are given two positive numbers N and M. Our task is to *find the M-th number whose repeated sum of digits of a number is N. *

**Problem description: **Here, we need to find the Mth number whose sum of digits till the sum becomes single digit is equal to N.

**Let’s take an example to understand the problem, **

**Input: **N = 4 M = 6

**Output: **49

## Solution Approach

A simple solution of the problem, is by finding all numbers and count the number whose sum of digits is N, and return m-th number.

Another solution to the problem is using formula to find M-th number whose sum of digits is equal to N,

*M-th number = (m-1)*9 + N*

## Program to illustrate the working of our solution,

## Example

#include <bits/stdc++.h> using namespace std; int main() { int n = 4, m = 6; int mNumber = (m - 1) * 9 + n; cout<<m<<"-th number whose repeated sum of digits of a number is "<<n<<" is "<<mNumber; return 0; }

## Output

6-th number whose repeated sum of digits of a number is 4 is 49

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