A program to find the number of times digit 3 occurs in each and every number from 0 to n is discussed here. Given a number n as input, count the number of 3s occurring in all the numbers from 0 to n.

For example,

Input: 100

Output: 20

The total number of 3s that appear from numbers 0 to 100 are {3, 13, 23, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 43, 53, 63, 73, 83, 93}

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Algorithm to find the number of times digit 3 occurs in each and every number

1. Input the number n from the user.
2. Initialize count = 0.
3. Repeat for all numbers from o to n.
4. Find if num % 10 == 3
5. Increment count
6. Divide the number by 10 and from step 4.
7. Return count.

The program to find the number of times digit 3 occurs in each and every number from 0 to n is given below.

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Time complexity: O(n)

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