CHAPTER 2 WHOLE NUMBERS
All numbers starting from 1 are called natural numbers.
PREDECESSOR AND SUCCESSOR
Subtracting 1 from a number gives its predecessor.
Adding 1 to a number gives its successor.
Note that 1, as a natural number, does not have a predecessor.
All the numbers from 0, 1, 2… are called whole numbers.
THE NUMBER LINE
Arranging the numbers on a line such that they are in an increasing order from left to right, having equal distance between them, forms a number line.
The distance between 0 and 1 is called ‘unit’ distance.
ADDITION USING NUMBER LINE
Consider 4+2. Start from 4 and make 2 jumps to the right. You get 6. And 4=2=6.
Therefore, to add, you move to the right.
SUBTRACTION USING NUMBER LINE
Consider 4-2. Start from 4 and make 2 jumps to the left. You get 2. And 4-2=2
MULTIPLAICATION USING NUMBER LINE
Again, consider 4x2. Start from 0 and move 4 units at a time to the right. Make 2 such moves and you’ll reach 8. And 4x2=8
PROPERTIES OF WHOLE NUMBERS
5x7= 7x5= 35
(2x5) x4= 2x (5x4)= 40
NOTE: Division by zero is not defined.