- Back in
recur(10) - Finished the recursive call, got back
"01" - Computes
"1" + "01", which is"101" - Stops and returns
"101"
Resulting call stack
r(1) returns "1"
r(3) dig -> "0" "0" + "1" returns "01"
r(10) dig -> "1" "1" + "01" returns "101
r(32) dig -> "2" "2" + ____