1, decimal notation:
This is the basic knowledge of this unit and what the students have learned before. Decimal counting means that the advance rate between every two adjacent counting units is 10. For example,1010,000 is 100,000,1000,000 is 1 million, and101 million is 10 million. This counting method can help students better understand and master the concept of large numbers. In particular, counting units and numbers are different concepts, which need students to distinguish clearly.
2. Read and write large numbers:
Reading and writing large numbers is the key content of this unit. Hundreds of millions of reading methods require students to score first, starting from a high position. Read level 100 million, then level 10,000, and finally level 1. 100 million series should be read according to the pronunciation of 100 million series, and then add a 100 million word at the end. Ten thousand series should be read according to the pronunciation of ten thousand series, and then a ten thousand word should be added at the end.
No matter how many zeros there are at the end of each stage, they will not be read. Other numbers have a zero or several consecutive zeros, all of which have only one zero. To write more than 100 million, students need to start from the top, first write 100 million, then write 10 thousand, and finally write one. There is no unit on any number, just write 0 on that number.
3, compare the size of the quantity:
Students need to master the method of comparing numbers. Two numbers with different digits, the one with more digits is larger and the one with fewer digits is smaller. When two numbers with the same number of digits are compared from the highest digit, the number of the highest digit is larger. If the highest digit is the same, compare the next digit until the size is compared.
4. Number of rewrites:
Students need to master the rewriting methods of numbers, including rewriting into numbers in units of 10 thousand or 100 million. At the same time, students also need to master the method of finding divisor, including omitting the mantissa after the ten thousand digits, depending on the number on the one thousand digits; The mantissa after omitting 1 100 million bits depends on the number on1100 million bits.
When using rounding method to find the divisor, it depends on whether the number of the highest digit in the omitted mantissa part is less than 5 or equal to or greater than 5. If it is less than 5, the mantissa is discarded and rewritten as a corresponding number of zeros; If it is equal to or greater than 5, advance 1, then discard the mantissa and rewrite it as a corresponding number of zeros.
The above are the main knowledge points of unit "Understanding Large Numbers". By learning these contents, students can better understand and master the concept of large numbers, and lay a solid foundation for future mathematics learning.