The teaching content of this course is based on students' learning "two digits minus two digits minus no abdication" and "two digits plus two digits plus carry". Students have a certain calculation basis and know how to use vertical calculation, so in this teaching, I mainly ask students to ask different questions through the mathematical information in the textbook examples, so as to further use the column formula for vertical calculation.
Formula of integer subtraction rule:
Integer subtraction is regular, and the same numbers should be aligned.
Reduce the time and difference greatly, and borrow less.
Minus ten and add it, and the result of addition and subtraction falls in the original position.
Be careful when borrowing continuously, and remember what is left when borrowing.