The first grade of primary school, the second volume of mathematics exercise book, 32 pages and 3 questions.
The sum of the number in the unit and the number in the tenth place is two digits of 10, which should be written in order. At the beginning, you can use a digital table to help, put all the beans of 10 in the unit, and then get the tenth place in turn. In this way, no matter what the sum of ten digits is, children can write it in an orderly way.