## Saturday, 12 January 2013

### NUMBER SYSTEM (3)

by Mr Johari

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The table above shows 2 categories of numbers as depicted by the blue and white shadings. identify these categories of numbers and give 2 additional examples each per category.

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post your responses as a 'comment'

1. White shadings - Prime Numbers ( examples: 11, 13...)
Blue shadings - Composite Numbers ( examples: 99, 100)
( As for one, since it is supposedly, neither prime nor composite, so I am currently unsure why is it under the blue shading...)

1. "One is neither a prime nor a composite number. A prime number is one
with exactly two positive divisors, itself and one. One has only one
positive divisor. It cannot be written as a product of two factors,
neither of which is itself, so one is also not composite. It falls
in a class of numbers called units. These are the numbers whose
reciprocals are also whole numbers." http://mathforum.org/library/drmath/view/57036.html

2. The white shadings are prime numbers (e.g. 5 and 7).
The blue shadings are composite numbers(e.g. 55 and 78).

3. White shadings are prime numbers. (e.g. 87,99)
Blue shadings are composite numbers (e.g. 4,6)
I agree with Xue qin, but they are using the sieve of erasthotenes(sorry if it's spelt wrongly) method, so they just shaded 1 blue, right?

1. "One is neither a prime nor a composite number. A prime number is one
with exactly two positive divisors, itself and one. One has only one
positive divisor. It cannot be written as a product of two factors,
neither of which is itself, so one is also not composite. It falls
in a class of numbers called units. These are the numbers whose
reciprocals are also whole numbers." http://mathforum.org/library/drmath/view/57036.html

4. Numbers in White are prime numbers (eg. 31, 67)
Numbers in Blue are composite number (eg. 45 , 78)
@lynette and @Xue qin , i got this explanation which answers your question . "One is neither a prime nor a composite number. A prime number is one
with exactly two positive divisors, itself and one. One has only one
positive divisor. It cannot be written as a product of two factors,
neither of which is itself, so one is also not composite. It falls
in a class of numbers called units. These are the numbers whose
reciprocals are also whole numbers." http://mathforum.org/library/drmath/view/57036.html

5. White numbers prime (7, 11)
Blue numbers composite(21, 93)

6. The numbers shaded white are prime numbers. e.g. 101,103

The numbers shaded blue are composite numbers. e.g 102, 104

7. White is prime numbers.
Blue is composite numbers.

1. e.g (White): 13,47
(Blue) : 68,99

8. The numbers in white are prime numbers such as 3,5,7
The numbers in blue are composite numbers like 4,6,8

9. White: Prime Numbers
Blue: Composite Numbers

10. White: Prime numbers (eg. 3,5,)
Blue: Composite numbers (eg. 1,4)

11. White: Prime numbers (2,3,5,7,11,etc)
Blue: Composite numbers (4,6,8,9,10, etc)

12. The numbers in white are prime numbers whereas the numbers in blue are composite numbers

13. White shadings- Prime numbers (eg. 2, 3, 5, 7 etc)
Blue shadings- Composite numbers (e.g. 4, 6, 8, 9 etc)