1
Natural numbers and zero
Textbook: Part 1, lesson 1, pp. 6–9
GoalKnow natural numbers, their decimal notation, places and classes; read and write multi-digit numbers.
New words
natural number · natural sondigit · raqamplace (digit position) · xonaclass (group of three places) · sinf
Explanation
Numbers used for counting objects are called natural numbers. They are written in the decimal system with the digits 0, 1, 2, ..., 9. In the sequence of natural numbers 1 is the smallest natural number and the sequence never ends; 0 is not a natural number. The places of a number are counted from right to left: units, tens, hundreds and so on, and every three places form one class: units, thousands, millions, billions. To read a number, say from left to right the number in each class followed by the class name; the name of the units class is not said.
Worked examples
Read 3 408 052: 3 million 408 thousand 52. The millions class holds 3, the thousands class 408 and the units class 52.
Write “12 billion 600 thousand 7”. There are no millions, so that class is filled with 000: 12 000 600 007.
Class activity
“Digit chain”: the teacher writes a 7–8 digit number. Pupils take turns reading one class (millions, thousands, units) and the team repeats the whole number.
Practice
1
Which is the smallest natural number? Is 0 a natural number?
The smallest natural number is 1; 0 is not a natural number.
2
Read the number 5 306 072 in words.
5 million 306 thousand 72
3
Write in digits: 9 million 40 thousand 5.
9 040 005
4
Why is there no largest number in the sequence of natural numbers?
If we add 1 to any natural number, we get a larger natural number.