during code why did test cases 3,4,5 are hidden

Question

due to hidden how can we find our mistakes that cause to failed test case

Answer 1

They are hidden because if you know all the answers, its pretty easy to write code that just satisfies the shown answers and not write good general working code like the excersize is trying to get you to.

You need to think of edge cases. Weird inputs that normally wont happen, but could. Take the code out of there and start giving it your own tests, you can come up with as many of those as you want.

Answer 2

If the test cases were to be unlocked, people could just cheat and make output based on the input, but not much coding.