When a two-digit number with a plus proposition number two main positive results do not exceed 100 in the landscape, and there is no test to be able to find the answer with telling reasonableness of answers.
When determining the amount of two-digit addition problem with two-digit number that sums up to 100 horizontal and without a test. You can answer that with a reasonable answer.
When the addition of two main problems with two main sum not to exceed 100 horizontally, and no treatment. Can find the answer and tell the validity of the answer.