Analysis: 42004200 is an eight-digit number. It can be divided into two levels: 4200 l 4200. According to reading, start from a high position and read step by step. There are 1 zeros in the middle of the number, or there are several zeros in succession, and only one zero is read. Do not read the zeros at the end of each level.

So, 30508070 reads: 4204200.

In China, it is customary to classify multiple digits with four digits, that is, starting from one digit, every four digits are regarded as the first level. Four, ten, one hundred, one thousand, one level; Ten thousand, one hundred thousand, one million and ten million are called ten thousand levels; Billions, billions, billions, billions is called billions. Grade 1, 10,000 and 100 million are called grades. The list is as follows:

Extended data:

First, the multi-digit reading rules:

1, reading, starting from a high position and reading step by step. When reading 100 million and 10 thousand levels, read according to the reading method of each level, just add a word "100 million" or "10 thousand" at the back.

2. There are 1 zeros in the middle of the number, or there are several zeros in succession, and only one zero is read.

Don't look at the 0 at the end of each level.

Second, the multi-digit writing rules:

1, the way to write multiple digits is to write from high to low, level by level.

2. Write 0 on any number without unit.

Third, the number of rewrites:

1, rewrite a number as "ten thousand".

To rewrite a number as "ten thousand", just remove the last four zeros and add the word "ten thousand". If there are less than four zeros at the end, add a decimal point after the ten thousand digits (before the thousand digits), remove the zeros at the end and add the word "ten thousand". ?

2. Rewrite a number into "100 million".

To rewrite a number as "100 million", just remove the eight zeros at the end and add the word "100 million". ? If there are less than eight zeros at the end, add a decimal point after 100 million digits (before 10 million digits), remove the zero at the end, and then add the word "100 million". ?

3. Find out the approximate figures:

Approximate a number by omitting the mantissa after 1 100 million bits. Just remove the number after 1 100 million bits according to the rounding method, and then write the word "1100 million".