It can be calculated by the algorithm of carry-free addition in the mathematics textbooks of lower grades in primary schools. The so-called carry-free addition means that the sum of two addends does not exceed ten, and the whole decimal number cannot be added into one. 33+65 digits: 3+5 = 8 digits: 3+6 = 9, 8+9 = 89, digits: 9+ 1= 10, 9+7= 16,10+6544.

Unit 6, Book 2, Mathematics, Senior One, People's Education Press, "Two digits plus one digit, integer ten (add without carry)" is mainly for students to learn the calculation process of add without carry. After mastering these methods, students can do oral calculations quickly.