Numeral system facts for kids
Quick facts for kids Numeral systems by culture 


Hindu–Arabic numerals  
Western Arabic Eastern Arabic Khmer 
Indian family Brahmi Thai 
East Asian numerals  
Chinese Suzhou Counting rods 
Japanese Korean 
Alphabetic numerals  
Abjad Armenian Cyrillic Ge'ez 
Hebrew Greek (Ionian) Āryabhaṭa 
Other systems  
Attic Babylonian Egyptian Etruscan 
Mayan Roman Urnfield 
List of numeral system topics  
Positional systems by base  
Decimal (10)  
2, 4, 8, 16, 32, 64  
1, 3, 9, 12, 20, 24, 30, 36, 60, more…  
A numeral system (or system of numeration) is a way to write numbers. Roman numerals and tally marks are examples. "11" usually means eleven, but if the numeral system is binary, then "11" means three.
A numeral is a symbol or group of symbols, or a word in a natural language that represents a number. Numerals differ from numbers just as the word "rock" differs from a real rock. The symbols "11", "eleven" and "XI" are different numerals, all representing the same number. This article tries to explain the different systems of numerals. Greek numerals and Roman numerals are among the systems that were long used, before the Hindu–Arabic numeral system largely replaced them.
Bases
Various symbols are used as numerals to make numbers. A system with base 10 (the normal decimal system), normally uses the symbols 0,1,2, 3, 4, 5,6, 7, 8, and 9. The numbers 0 to 9 can be written as one symbol, 0 ... 9. To count past 9, symbols have to be put together. 10 can be seen as 1 in the tens' place and 0 in the ones' place, or as 1 times 10^{1} plus 0 times 10^{0}. With a base of 2, only the symbols 0 and 1 are used. 10 in base 2 notation is therefore 1 times 2^{1} plus 0 times 2^{0}. This is the same as 2, in the base 10 notation.
For bases bigger than 10, capital letters are used as symbols. For example, the hexadecimal numeral system (base 16) uses the numerical digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F.
Today, mainly base 10 is in use. Computers use binary and people who study computers often use octal and hexadecimal numeral systems. Ancient Sumer used sexagesimal (base 60). Mesoamerica used base 20.
Most electronic calculations are done in binary (base 2), but most people do calculations in decimal (base ten).