Page 4 - ตัวอย่าง Math Solution 1

1.1 Positive Integers

The number starts with a pattern of increasing by 1 ; 1, 2, 3, 4, 5, 6, sometimes called

the counting numbers or natural numbers.

The counting numbers are 1, 2, 3, …. 1 is the least counting number and other counting

numbers related to 1 are:

1+1 is greater than 1 represented by 1+1 = 2; therefore, 2 is greater than 1, or 2 > 1.

2+1 is greater than 2 represented by 2+1 = 3; therefore, 3 is greater than 2, or 3 > 2.

3+1 is greater than 3 represented by 3+1 = 4; therefore, 4 is greater than 3, or 4 > 3.

Positive integers can be written on a number line as shown below:

1 2 3 4 5 6 7 8

For any counting number, it’s always got a bigger neigbour; therefore the counting numbers do
not have any upper limit or they go to infinity.

The counting numbers are also called positive integers.

Consider these questions, then discuss with your friends.

1. How many positive integers are less than 50?
2. How many positive integers are greater than 50 but less than 100?

3. What is the greatest positive integer less than 50?
4. What is the least positive integer greater than 50?

Example 1

1. Find the positive integers from 5 to 9.

The positive integers from 5 to 9 are 5, 6, 7, 8 and 9.
Answer

2. Find the positive integers between 12 and 17.
The positive integers between 12 and 17 are 13, 14, 15 and 16.
Answer
3. Find the positive integers that are less than 8.

The positive integers that are less than 8 are 1, 2, 3, 4, 5, 6, and 7.
Answer
4. Find the positive integers that are greater than 20.

The positive integers that are greater than 20 are 21, 22, 23, 24, 25, 26,...
Answer

8 Math Solution 1 Book 1