Understanding of the number 1 1-20;
1, number: according to the number of objects, it can be represented by 1 1-20.
2. Sequence: 1 1-20 The sequence is: 1 1, 12, 13, 14, 15,/kloc.
3. Comparison size: comparison can be made according to the order of numbers, and the last number is always greater than the previous number, or according to the composition of numbers.
4. Composition of the number 1 1-20: All of them are composed of 1 tens and several ones, and 20 is composed of two tens. Such as: 1 ten and five 15.
5. Number of digits: the first digit on the right is one digit, and the second digit is ten digits.
6. 1 1-20 How to read each number: read dozens of digits from high places and several digits. Pronunciation of 20, 20 is pronounced: 20.
7. Write numbers: When writing numbers, write against them. If there are 1 tens, write 1 on the ten, and if there are two tens, write 2 on the ten. If there are several 1, write a few on each bit, and if there is no unit on each bit, write a 0.
8. Ten plus several, ten plus several and the corresponding subtraction.
The calculation method of (1) 10 plus several and the corresponding subtraction: 10 plus several gets ten, ten MINUS several gets ten, and ten MINUS ten gets several.
For example, 10+5= 15,17 =10, 18- 10=8.
(2) Calculation method of ten plus several and corresponding subtraction: When calculating ten plus several and corresponding subtraction, you can use the composition of numbers to calculate, or you can add or subtract the numbers in units of one and then add the whole ten.
(3) Add and subtract the names of each part:
In the addition formula, the numbers before and after the plus sign are called addends, and the numbers after the equal sign are called sums.
In the subtraction formula, the number before the minus sign is called the minuend, the number after the minus sign is called the subtraction, and the number after the equal sign is called the difference.
9. Solve the problem
To find how many numbers are between two numbers, you can use counting method or graph method. You can also use the calculation method (subtract large numbers from 1).