Consecutive numbers are numbers that are in order. for example, 123456789.
When adding consecutive numbers, you add the two numbers on the outside. Then you add the next two numbers closest to the numbers you just added, and so on. If you added right, all the numbers should be the same. ( if there is one number is different, it is okay) After you add like I said in the sentence before , add the numbers that you got from adding from the outside to the center. And that is how you add consecutive numbers.