I had the same issue too. The code I have works but will kick the number back if it is too large. Maybe there is some other way you have to solve it?

Thanks for the response. What do you think is wrong with the code provided?

I agree with Markus.
I would recommend adding a sample test with n=25 and m=200. This will result in a condition where m is exactly equal to a multiple of n. Without it, the final test will sometimes pass and sometimes fail because the random test does not always include a scenario where m is an exact multiple of n.

Assert.AreEqual(700, Kata.SumMul(25, 200));

I think that change will eliminate the confusion people are encountering.

The description is misleading: positivity is not an assumption, it must me validated for by your code.

:)

Hardly an issue. You need better code.

I was able to solve the code, but the server timed out a lot when running the tests. It seemed like a lot of the sample tests were working with very large numbers. Maybe that had something to do with it? Not sure.