Numbers Up to 999
We use
numbers for counting things. In class 1, we have studied 2-digit numbers up to
99. Here, we will study 3-digit numbers up to 999.
We know that
99 is the greatest 2-digit number. When we add 1 to the greatest 2-digit
number, we get the smallest 3-digit number.
99 + 1 = 100
100 is the
smallest 3-digit number. 999 is the largest 3-digit number.
When we need
to count numbers which are greater than 99 and less than 1000, we use 3-digit
numbers to count them. 3-digit numbers start from 100 and end at 999.
A 3-digit
number has 3 places. Ones (O), tens (T) and hundreds (H).
The number
623 can be written as:
Number Names
The numbers
can be written in numeral form and in words. The numbers written in words are called
number names.
The number
name of 148 is: One hundred forty-eight
The number
names of a few numbers are given in the table.
|
Numbers |
Number Names |
|
356 |
Three hundred fifty-six |
|
517 |
Five hundred seventeen |
|
832 |
Eight hundred thirty-two |
|
635 |
Six hundred thirty-five |
Expanded Form
We know that
the number 485 has 4 hundreds, 8 tens and 5 ones.
485 = 4
hundreds + 8 tens + 5 ones
= 400 + 80 + 5
This is the
expanded form of 485 and 485 is called the standard form of 400 + 80 + 5.
Similarly,
the expanded form of 729 is: 700 + 20 + 9
Numbers on Abacus
Let us
represent the number 223 on abacus.
We have 223
= 2 hundreds + 2 tens + 3 ones
So, draw 2
beads on hundreds rod, 2 beads on tens rod and 3 beads on ones rod.
Now, can you
write the number shown on the given abacus?
Yes, it is 5
hundreds + 4 tens + 3 ones = 543
Place Value and Face Value
The place
value of a digit is determined by its position in the number.
Let us find
the place value of each digit in the number 785.
Similarly,
the place value of 3 in 371 is 300 and the place value of 9 in 397 is 90.
The face
value of a digit remains the same as the digit. No matter the digit is situated
at hundreds place, tens place or at one place.
Comparing Numbers
We know
that:
A 3-digit
number is always greater than a 2-digit number.
For example,
101 > 99
If we want
to compare two numbers with the same number of digits, then start comparing
from hundreds digit.
1. If
hundreds digit of a number is greater, then it is greater.
2. If the
hundreds digit is the same, then compare tens digit. The number with greater tens
digit is greater.
3. If the
tens digit is also the same, then compare ones digit. The number with greater
ones digit is greater.
For example,
let us compare 734 and 718.
Here, 734
> 718
Ordering Numbers
We can order
numbers from smallest to largest and from largest to smallest.
Ascending Order
When numbers
are written in the order from the smallest to the largest, they are said to be
in increasing or ascending order.
485, 589,
643 and 753 are in ascending order.
Descending Order
When numbers
are written in the order from the largest to the smallest, they are said to be
in decreasing or descending order.
832, 745,
467 and 394 are in descending order.
Forming Largest and Smallest Numbers
From the 3
given digits, we can form the largest or the smallest 3-digit number.
To form the
largest number, put the numbers in descending order.
Example 1:
Form the largest
number using the digits 3, 8 and 1.
Solution: To form the largest number, put the
3 given digits in descending order. We get 831. Which is the largest 3-digit
number.
To form the smallest
number, put the numbers in ascending order.
Example 2:
Form the smallest
number using the digits 2, 6 and 4.
Solution: To form the smallest number, put the
3 given digits in ascending order. We get 246. Which is the smallest 3-digit
number.
If 0 is one
of the digits, then put 0 in the tens place.
Example 3:
Form the smallest
number using the digits 5, 7 and 0.
Solution: To form the smallest number, put the
3 given digits in ascending order. We get 057. But this is 57. Which is a
2-digit number. So, put 0 in the tens place and 5 in the hundreds place. We get
507 as the smallest 3-digit number formed using the digits 5, 7 and 0.
Numbers Before, After and In Between
If we take three
numbers (41, 42, 43) in order, then 41 is before 42 and 43 is after 42. 42 is
in between 41 and 43. Look at the following table.
|
Before |
Number (In between) |
After |
|
90 |
91 |
92 |
|
178 |
179 |
180 |
|
429 |
430 |
431 |
|
909 |
910 |
911 |
Class 2 Number System Test
Maths
Quiz for Class 2 Numbers
Class 2 Number System Worksheet