Thanks Johan and Jason! I was looking for the math typesetting for this kata but couldn't find it.
The math typesetting really helped!

Thank you mauro for this explanation. I'm new to making katas so these are really helpful.
I've changed the test framework and also use pre-computed expected values to test the results.

Thank you, I've changed it. Whenever the result is valid, it use will assert_approx_equals, otherwise it uses assert_equals to check for 'invalidity'

Thanks for the feedback, what do you propose for the test framework and what do you mean by user can modify the input?

Oh wow, totally missed that. Thanks!

Sorry for that, it's fixed. Thanks for notifying.

Ahh, sorry I misunderstood you. I changed the first test to test.assert_equals(number_of_sets(1, 1), 0).

Thanks for notifying. I have updated the description to be 'non-zero'.

Thanks for notifying. I have updated the description to be 'non-zero'.

Thanks for notifying, I've fixed it.