Numbers are the basic unit of mathematics. A number system is a writing system for expressing numbers. Do you want to know how things are measured, counted or compared? Let's find out!
Indian Place Value System
1000000, 10000000, 100000000 lead to new places called ten lakhs, crore and ten crore, respectively.
Expanded Form
 Let us consider a number 123.
 The number can be written as: (1X100)+(2x10)+(3x1)
That is, 1 is at hundreds' position, two is at tens' position and 3 is at ones' position. If we put it in ones' period we get:
One’s Period 

Hundreds 
Ones 

1 
0 
0 
2 
0 

3 
Hence, the number in expanded form is one hundred and twentythree.
Example 1: Write the number 2398257 in words.
Answer: Twentythree lakhs ninetyeight thousand fiftyseven.
Example 2: Write the number name 'thirty crores fiftyfour lakhs eightyseven thousand two hundred sixtyone in figure.
Answer:
Ten Crores 
Crores 
Ten Lakhs 
Lakhs 
Ten Thousand 
Thousand 
Hundred 
Tens 
Ones 
Number 
3 
0 
5 
4 
8 
7 
2 
6 
1 
305487261 
The International Place Value System
In International Place Value System, the digits are read from left to right. That is billions...,millions..., thousand...
Example 1: Write fiftyfive million sixtyfour thousand forty nine in figures.
Answer: 55,064,049
Example 2: Write 23,467,854 in expanded form.
Answer: TwentyThree Million, Four Hundred and SixtySeven Thousand, Eight Hundred and Fifty Four.
Roman Numerals
 You can subtract only one number. You can't get a 3 by writing IIV.
Example 1: What is the Roman Numeral for 33?
Answer: XXXIII
Example 2: What does the Roman Numeral LXXIV represent?
Answer: 74
Practice These Questions
 Write the following in figures in the International system:
 four thousand, two hundred and ten
 Thirtyone thousand, four hundred and twelve
 Two hundred and fortyfour thousand, three hundred and one
 Three million, two hundred and twentyone thousand, two hundred and fifteen
 Fiftyfour million, one hundred and eleven thousand, three hundred and sixtytwo
 Two hundred and fourteen million, two hundred and seventytwo thousand, seven hundred and eleven
 Write the following in expanded form in Indian Place Value System (i) 76589342; (ii)65286456; (iii)84257834
 Read the Roman Numeral Dial and write the time
 Draw the hours and minutes hand in the roman numeral clock.
a)1:55 b)3:05 c)6:30
Recap
 The first period, called ones’ period, is formed with the first 3 digits of the number.
 The second period, called thousands period, is formed with the next 3 digits of the number.
The third period, called millions period, is formed with the digits after thousands
 A Roman Numeral can't be repeated more than three times.
 V, D, and L are never subtracted
 There is no symbol for zero and no place value in Roman Numerals.