Page 31 - ICSE Math 6

2 Natural Numbers and Whole

Numbers

Key Concepts

• Natural Numbers and Whole Numbers • Properties of Whole Numbers
• Addition, Subtraction and Multiplication of Whole • Division Algorithm
Numbers on a Number Line

We have already learnt about numbers, their place value, face value, estimation, etc. In this chapter,
we will learn about numbers and their properties in detail. We will also learn addition, subtraction
and multiplication of numbers on a number line.

Natural Numbers

The numbers 1, 2, 3, 4, ... are called counting numbers. Counting of these numbers comes naturally
to us. Therefore, mathematicians also called these numbers natural numbers. Hence, the numbers 1,
2, 3, ..., 1,000, ..., 10,00,00,000, ..., etc. are called natural or counting numbers.

Successor and predecessor of natural numbers
The successor of a natural number is the natural number that comes Try These
just after it. For example, the successor of 3 is 4. The predecessor of 1. Write the successor of first
a natural number is the natural number that comes just before it. For five natural numbers.
example, 12 is the predecessor of 13. To find the successor of a number 2. Is 999 predecessor of 1,000?
we add 1 to it and to find its predecessor we subtract 1 from it. 3. What is the predecessor of
successor of 19,453?
The number 1 is the only natural number which has a successor but 4. Can we have a last natural
no predecessor because on subtracting 1 from it, we get 0 which is not number? Why?
a natural number.

All natural numbers except 1 have both successor and predecessor.

Whole Numbers

All natural numbers along with 0 are called whole numbers. Every natural number is a whole number
but, on the other hand there exists a whole number ‘0’ which is not a natural number. Thus, as a whole
number 1 has the predecessor 0.

Addition of whole numbers on a number line
We can add two or more whole numbers on a number line. Maths Info
Let’s add whole numbers 3 and 5. The word zero originated from
Step 1: Draw a number line as shown. the Hindu word sunya which
means ‘void’. Then sunya was
translated into the Arabic sifr,
0 1 2 3 4 5 6 7 8 9 10 which when translated to Latin
Step 2: First move three units to the right of ‘0’ to reach at 3. gave zero.

0 1 2 3 4 5 6 7 8 9 10

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