The analysis process is as follows:
When counting, count to dozens, and you want to know what the next integer is.
Between 30 and 40, excluding 30 and 40, so * * * has nine numbers:
3 1、32、33、34、35、36、37、38、39。
Extended data
Number sequence within 100: from the right, the first digit is one digit, the second digit is ten digits, and the third digit is one hundred digits.
Read and write numbers within 100:
Number sequence within 1 and 100: from the right, the first digit is one digit, the second digit is ten digits, and the third digit is one hundred digits.
2. Both reading and writing are high. When reading, you should read hundreds of miles, dozens of miles, a few digits, and don't read the last 0; When writing numbers, the hundredth digit writes hundreds, the tenth digit writes tens, the first digit writes ones, and the last counting unit is empty, so write a zero there.