Yep. Problem between keyboard and chair again. Thanks!

I still have this only one test failing showing:
Expected: -267383598
But was: 9828066929
or
Expected: -1030890533
But was: 9889935162

Putting the test in the try-catch clause does not make a fix for that test :P
Do we want the overflow to happen? if so, why?

same happening with mine code... all green but this test, where the results are weird:
Expected: 875597558
But was: 1356437483
or
Expected: -705845463
But was: 1247101567
it is caused by System.OverflowException with message: "Arithmetic operation resulted in an overflow." But seems that the negative value experience an overflow itself?
Do not quite understand.....