chapter 4

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Chapter 4:

Numeration Systems

Mathematical Systems

A mathematical system is made up of three components:

1.A set of elements;

2.One or more operations for combining the elements;

3.One or more relations for comparing the elements.

Numeration Systems

• A number system has a base . Our system is base 10, but other bases have been used (5, 20, 60)

• Simple grouping system uses repetition of symbols, with each symbol denoting a power of the base (ex Egyptian)

• Multiplicative grouping uses multipliers instead of repetition (ex Traditional

Chinese)

Positional Systems

In a positional system , each symbol (called a digit ) conveys two things:

1) Face value : the inherent value of the symbol (so how many of a certain power of the base)

2) Place value : the power of the base which is associated with the position that the digit occupies in the numeral

Hindu-Arabic System

• Our system, the Hindu-Arabic system , is a positional system with base 10 .

• Developed over many centuries, but traced to Hindus around 200 BC

• Picked up by Arabs and transmitted to

Spain

• Finalized by Fibonacci in 13 th century

• Widely accepted with invention of printing in 15 th century

Different Bases

• Our number system is decimal, so the base is 10. The digits are 0, 1, 2, 3, 4, 5,

6, 7, 8, 9.

• With a different base b , the digits are 0, 1,

…, b -1.

• Some special bases: 2 ( binary ), 8 ( octal ),

16 ( hexadecimal )

What do we do with different number bases

• Convert a number in a different base to decimal

• Convert a decimal number to a different base

• Add numbers with same base (be sure to carry if needed)

• Subtract numbers with same base (be sure to regroup if needed)

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