1. Pupil counter is a kind of counter used by pupils, including counting beads and arched bead-piercing rods. There are "tens" and "bits" on the counter. A bead on the tenth digit means 1 digit, and 1 bead on the unit means 1 digit. There are 10 beads at the tenth position and the unit position respectively.
2. For 15, you can dial 1 bead in ten digits and 5 beads in one digit, indicating 1 ten digits and 5 ones, that is, 15. A counter can not only represent a number within 20, but also represent a larger number, with a maximum of 1 10. There are 10 beads at the tenth position, which is 10 at the tenth position and 100 at the digit position, which is 10, which is 10,100.
How to read the first and fourth numbers:
1, read from the high place in order, read thousands on thousands, read hundreds on hundreds.
2. There is a zero or two zeros in the middle, and only one "zero" is read;
No matter how many zeros there are, don't read the last number.
Second, four-digit writing:
1, written in order from the high order;
2. Write thousands, hundreds, with a "0" in the middle or nothing at the end.