can someone please explain this code to me i'm clueless

Question

fun alwaysReturnsNull(position: Int):
String? {
if ((position % 10) == 0) {
when (position) {
10 -> "one"
20, 30 -> "two"
else -> "three"
}
}
return null
}
fun returnsNullableString(position: Int):
String? {
if ((position % 10) == 0) {
return when (position) {
10 -> "one" 20, 30 -> "two" else -> "three"
}
}
return null
}

Answer 1

The first always returns null. The if statement does not have any effect on the result. The if statement is entered for position of 0, 10, 20, 30, 40, ... The when statement produces values always that are ignored. "one" for 10, "two" for 20 & 30, and "three" for all others.

Answer 2

The second is similar, but the if and when have an affect. Now, the result of the when are returned so 0 yields "three", 1 to 9 yield null, 10 yields "one", 11 to 19 yield null, 20 yields "two", 21 to 29 yield null, ...