Non-carry addition:

Find single digits: Add the single digits of the addend and the single digits of the addend.

Ten-digit addition: Add the ten digits of two numbers.

If the sum of digits is greater than or equal to 10, carry is required, that is, ten digits plus 1.

If the result of adding ten digits is greater than or equal to 10, then it needs to be rounded off, that is, hundred digits plus 1.

For example:17+23 = (1+2)+(7+3) =12, and the result is 20.

Subtraction without abdication:

Find single digits: subtract the minuend and the single digits of the minuend.

Decimal number subtraction: Subtract the decimal number of two numbers.

If the result of single digit subtraction is less than 0, you need to borrow, that is, borrow from ten digits 1.

If the result of subtracting ten digits is less than 0, you need to borrow, that is, borrow 1 from the hundred digits.

For example: 25-16 = (2-1)+(5-6) =-4, and the result is 19.

Basic skills of primary school mathematics:

1, finding the law: finding the law is one of the important skills for primary school students to learn mathematics. By observing a set of numbers or figures, students can find the law and predict the next number or figure. This skill can help primary school students better understand mathematical concepts and ideas and improve their observation and thinking ability.

2. Simple calculation: Simple calculation is a fast calculation method. By simplifying the calculation process and oral calculation skills, the calculation speed and accuracy can be improved. For example, rounding, extracting common factors, and in turn using the law of multiplication and distribution, students can get the results faster.

3. Know the clock: Knowing the clock is one of the important skills for primary school students to learn the concept of time. By learning how to read the hour hand, minute hand and second hand, and how to express time, pupils can better understand the concept and measurement method of time.

4. Understanding RMB: Understanding RMB is one of the important skills for primary school students to learn the concept of money. Pupils can better understand the concept and calculation method of currency by learning the face value and conversion method of RMB.

5. Sorting: Sorting is an important skill for sorting and analyzing data. Pupils can better understand the concept of data and statistical analysis methods by sorting the data according to different categories.