Loading collection data...
Collections are a way for you to organize kata so that you can create your own training routines. Every collection you create is public and automatically sharable with other warriors. After you have added a few kata to a collection you and others can train on the kata contained within the collection.
Get started now by creating a new collection.
I did that kata yesterday, and spent a fair amount of time reading up on best ways to randomize stuff. From what I read, math.Random is actually pretty bad at randomizing stuff.
That being said, I did see kata solutions using random which were accepted. How many times did you try submitting your answer? Maybe try again? Otherwise, there's probably something else wrong. If you console log your array a bunch of times in a row, you will probably see some patterns. 1 number out of 15 being in the same spot in a column 30% of the time is wrong; any number being in a column at all only has a 33% chance (and 25%-ish for the middle column).