Introduction
Zero
- Zero is the smallest counting number. It is represented as 0.
- The image below shows a jar with two balls – black and white
- Now if you remove the two balls, the jar contains 0 balls—
One-digit numbersNumbers from 0 to 9 are one-digit numbers.
Number lineA number line can be defined as a straight line with numbers placed at equal distance along its length.
Place value- The value of each digit in a number is known as place value.
- Starting from right, the first place is units or ones (O) and the second place is tens (T).
Example: The place value of the two-digit number 13 will be as follows:
Two-digit numbers- Numbers from 10 to 99 are two-digit numbers.
- Here are some examples for two-digit numbers.
- How to get the number 18?
- What number do you get when 3 tens is added to 4 ones?
- What number do you get when 5 tens is added to 1 one?
- What number do you get when 7 tens is added to 2 ones?
- What number do you get when 8 tens is added to 6 ones?
- What number do you get when 9 tens is added to 8 ones?
- See the following examples.
Given that
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
Greater than
- Greater than Which number is greater: 7 or 10?
- We can identify the greater number using a number line.
- 10 lies on the right side of 7, so 10 is greater than 7 and we write it as 10 > 7.
Less than- Which number is smaller: 34 or 53?
- We compare the numbers using a number line.
- 34 lies on the left side of 53, so 34 is smaller than 53 and we write it as 34 < 53.
Equal to- If the two numbers given are same, we say that the numbers are equal.
- We can say that 7 is equal to 7 and write it as 7 = 7
Example: Are the numbers 19 and 91 equal?
The given numbers are 19 - Nineteen and 91 - Ninety-one. They are not same. So, 19 and 91 are not equal.
Writing numbers in reverse order.9, 8, 7, 6, 5, 4, 3, 2, 1, 0 is the backward order of one-digit numbers.
99, 98, 97, 96, 95, 94, 93, 92, 91, 90, 89, _______, 10 is the reverse order of two-digit numbers.
Ascending and descending orders.- Ascending order means arrangement of numbers from small to big.
- Descending order means arrangement of numbers from big to small.
Examples:
- Arrange the given numbers in ascending order: 54, 28, 47, 87, 18, 64
- Arrange the numbers from the smallest to the biggest or largest.
So, the order is 87, 64, 54, 47, 28, and 18. - Arrange the numbers 45, 12, 56, 84 in descending order.
- Arrange the numbers from the biggest or largest to the smallest.
So, the order is 84, 56, 45, 12.
Just before, Just after, and In-between
- If the numbers are 13, 14, and 15,
- 13 comes just before 14.
- 15 comes just after 14.
- 14 lies in between 13 and 15.
Skip countingNumbers obtained by adding the same number.
Example:
- 2, 4, 6, 8, 10 are the numbers we get by skip count of 2.
- 3,6,9,12,15 are the numbers we get by skip count of 3.
- 4, 8, 12, 16, 20 are the numbers we get by skip count of 4.
- 5, 10, 15, 20, 25 are the numbers we get by skip count of 5.
- 10, 20, 30, 40, 50 are the numbers we get by skip count of 10.