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# Decimal Numeral System

by Ron Kurtus (revised 8 June 2015)

The * decimal numeral systen* is a system of numbers and counting based on

**10**(deci-). We use a system of numbers or

*numeral system*that is based on 10—or decimal numerals—because we have 10 fingers for counting.

Numbers listed in a sequence start from digit 0 and go through 9. Then they start at the next lelve.

A * number* is a quantity that answers the question: "How many are there?"

Each number has its own name. *Counting* is putting the numbers in an order where the next number is one more than the previous. For each number name, there is a symbol, which we consider the actual number.

Questions you may have include:

- How do we count?
- What are the number names and symbols?
- What is the decimal numeral system?

This lesson will answer those questions.

## Counting

Although it seems trivial, it is a good idea to look at counting to understand the number system and addition. Children start counting on their fingers: one, two, three, four, five, and so on. Each number in counting on your hand is one finger more than the previous.

Once you have established symbols for numbers, counting becomes easier, because you can then write it down.

## Names and symbols of numbers

Each number has a name and a symbol, which is the way the number is written.

### Roman numerals

In ancient Rome, they used Roman numerals as symbols for numbers. They would write down counting to ten as: I, II, III, IV, V, VI, VII, VIII, IX, X. Although it has some logic to it, it also is cumbersome and not convenient for such arithmetic operations like multiplying and dividing.

### Arabic numerals

The Arabic system of numbers or Hindu-Arabic numerals was more convenient for the various operations. Modernized versions of those numbers are the ones we use today.

## Name |
## Symbol |
## Name |
## Symbol |
## Name |
## Symbol |

zero | 0 | ten | 10 | twenty | 20 |

one | 1 | eleven | 11 | twenty-one | 21 |

two | 2 | twelve | 12 | twenty-two | 22 |

three | 3 | thirteen | 13 | twenty-three | 23 |

four | 4 | fourteen | 14 | twenty-four | 24 |

five | 5 | fifteen | 15 | twenty-five | 25 |

six | 6 | sixteen | 16 | twenty-six | 26 |

seven | 7 | seventeen | 17 | twenty-seven | 27 |

eight | 8 | eighteen | 18 | twenty-eight | 28 |

nine | 9 | nineteen | 19 | twenty-nine | 29 |

## Decimal numeral system

Most people use the decimal numeral or number system that is based on 10. The reason is because we have 10 fingers. When you count on your fingers, you start with one and continue until you have all ten fingers up. Then you start over with one finger up for 11.

>> The numbers 0 to 9 have unique names. The numbers from 10 to 19 have variations of the 0 to 9 names, including seven that are "teens". Afterwards, the names of the numbers seem pretty consistent. The number 20, is twenty, and 21 is twenty-one. Likewise, the number 30 is thrity, 31 is thrity-one, 32 is thrty-two, and so on.

Going on to the next level, 100 is one hundred, 101 is one hundred one, 123 is one humdred twenty three.

2305 is two thousand three hundred five.

Note: Although many people say "two thousand three hundred **and** five" the word and should not be used. It is reserved for indicating decimals. For example, 326.5 is three hundred twenty six **and** five-tenths.

### Advantage of Hindu-Arabic numerals

The question is: why is ten designated as 10, when it represents all fingers up? Why isn't it like the Roman numeral X? Using 10 for ten and starting with 11 for eleven is what makes the Hindu-Arabic numerals so effective in mathematical operations.

### Binary numeral system

The binary numeral systems is used in computers, because electronic circuits can do rapid calculations using ON and OFF switches. They use 1 as ON and 0 as OFF. Counting from zero to eight in the binary system goes: 0, 1, 10, 11, 100, 101, 110, 111, 1000.

It is much easier for the computer circuits to use the binary system than the decimal system.

## Summary

A number is a quantity, and each number has its own name. Counting is putting the numbers in an order where the next number is one more than the previous. For each number name, there is a symbol or actual number. We use the decimal numeral system, which is based on 10, because we have 10 fingers for counting.

Make every action count

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numeral_system.htm**

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## Where are you now?

## Numbers and the Numeral System