Cardinal numbers

Cardinal numbers
A cardinal number is a number used in counting to indicate quantity. A cardinal number answers the question "How many?" Also called a counting number or a cardinal numeral.
Though not all style guides agree, a common rule is that cardinal numbers one through nine are spelled out in an essay or article, while numbers 10 and above are written in figures. An alternative rule is to spell out numbers of one or two words (such as two and two million), and use figures for numbers that require more than two words to spell out (such as 214 and 1,412). In either case, numbers that begin a sentence should be written out as words.
Regardless of which rule you choose to follow, exceptions are made for dates, decimals, fractions, percentages, scores, exact sums of money, and pages--all of which are generally written in figures. In business writing and technical writing, figures are used in nearly all cases.
List of Cardinal Numbers
The cardinal numbers refer to the size of a group:

• 
  zero (0)
  
• 
  one (1)
  
• 
  two (2)
  
• 
  three (3)
  
• 
  four (4)
  
• 
  five (5)
  
• 
  six (6)
  
• 
  seven (7)
  
• 
  eight (8)
  
• 
  nine (9)
  
• 
  ten (10)
  
• 
  eleven (11)
  
• 
  twelve (12)
  
• 
  thirteen (13)
  
• 
  fourteen (14)
  
• 
  fifteen (15)
  
• 
  twenty (20)
  
• 
  twenty-one (21)
  
• 
  thirty (30)
  
• 
  forty (40)
  
• 
  fifty (50)
  
• 
  one hundred (100)
  
• 
  one thousand (1,000)
  
• 
  ten thousand (10,000)
  
• 
  one hundred thousand (100,000)
  
• 
  one million (1,000,000)
  

The Difference Between Cardinal Numbers and Ordinal Numbers