1, law of addition: be careful when adding integers, and the number of digits at the bottom of the horizontal line should be neat. Don't forget to add one plus ten. The figures add up neatly, don't forget to bring them.
2, the law of subtraction: integer subtraction should be careful, the numbers above the horizontal line should be neat, subtract one and borrow ten, don't forget, digital subtraction depends on the level, remember if it is not enough.
3, the law of multiplication: integer multiplication first counts zero, add a complement to look up and down, add up and multiply up and down, it is not difficult to master integer multiplication.
4. Division rule: integer division is particular. The front and back positions are opposite to Qi Xin. First, look at whether the back bits are enough, and then look at the front bits carefully.
Four operational skills:
1, Application of associative law and distributive law: In elementary arithmetic, addition and multiplication are two basic operations, which have the characteristics of commutative law and associative law. Multiplication also has the characteristics of distribution law, so we can combine the associative law of multiplication with distribution law to simplify the calculation.
2. Rule of removing brackets: In elementary arithmetic, brackets are the key to the operation order. Depending on whether the parentheses are preceded by a plus sign or a minus sign, we can adopt different rules to remove the parentheses. If there is a plus sign in front of the brackets, we can remove the brackets directly; If there is a minus sign in front of the brackets, we need to change all the numbers in the brackets before deleting them.
3. Application of multiplication and division: multiplication and division is an important operation skill, which can multiply a number with two or more numbers respectively, and then add or multiply the results. We can use the law of multiplication and distribution to simplify the calculation.
4. Nature of division: In division, if the divisor can be divisible by 2, 4, 8, etc. We can convert division into multiplication to calculate. For example, when the divisor is even, we can multiply the divisor and dividend by 2 at the same time, and then convert the calculation into multiplication.
5. Split method: In elementary arithmetic, some numbers can be split into the form of addition or multiplication of two or more numbers, which can simplify the calculation. For example, 12 can be decomposed into multiplication of 3 and 4, which can avoid multiple calculations.