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DataWeave programming challenge #6: Using tail-recursion to get the factorial of a number


Other posts from this series:


In this post:


Try to solve this challenge on your own to maximize learning. We recommend you refer to the DataWeave documentation only. Try to avoid using Google or asking others so you can learn on your own and become a DataWeave expert!


Consider the following input payload (can be of txt format):


Explanation of the problem

  1. Create a tail-recursive function to get the factorial of each positive number from the payload.

  2. Sum the results.

  3. Retrieve the digits/characters located at positions 20-25.

  4. Make sure to return a number and not a string.

  5. Numbers 0 or less won't be calculated.

For example:

  • The factorial of 3 is 6 (3 x 2 x 1)

  • The factorial of 5 is 120 (5 x 4 x 3 x 2 x 1)

  • The factorial of -6 won't be calculated so the result will be 0

  • And so on

  • Once the results are summed (6 + 120 + 0...), extract the digits at indexes 20 to 25.

  • Return this last 6-digit number.

Expected output

In this case, the expected output would be:



If you're stuck with your solution, feel free to check out some of these clues to give you ideas on how to solve it!

Clue #1

Clue #2

Clue #3

Clue #4

Clue #5


If you haven't solved this challenge yet, we encourage you to keep trying! It's ok if it's taking longer than you thought. We all have to start somewhere ✨ Check out the clues and read the docs before giving up. You got this!! 💙

There are many ways to solve this challenge, but you can find here one of my solutions!

Solution #1

Feel free to comment your code below for others to see! 😄

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