Numeric grading is a way of reading Arabic numerals for people to remember. On the basis of numerical system (numerical order), read and write numbers according to the principle of three-digit or four-digit grading.

Usually, in the writing of Arabic numerals, commas or spaces are used as the marks of each number level, and the numbers are separated from right to left, for example, 3,000,003,003,000; 271500 0000 2.7 billion150,000.

The decimal counting method of extended data is characterized by "full 10 into one". In other words, every 10 unit forms a higher unit adjacent to it. That is, 10 is called "ten", 10 is called "hundred", 10 is called "thousand" and 10 is called "ten thousand".

One (a), ten, hundred, thousand, ten thousand, one hundred thousand, one million (trillion), ten million, one billion, ten billion, one hundred billion ... are all units of counting.

Numbers mean that when writing numbers, the numbers are arranged side by side in a line, and each number occupies a position. These positions are called numbers. Starting from the right end, the first place is the unit, the second place is the tenth place, the third place is the hundred places, the fourth place is the thousand places, and the fifth place is the ten thousand places, and so on. This shows that the concept of counting unit and number is different.

However, their relationship is very close. "4" means 400 in hundreds, "7" means seven tens in tens, and "5" means five ones in tens.