What is a prime number? How do I recognize a prime number? what makes 7, for instance, a prime number?

It is any number only divisible by itself and 1 (giving whole number results). A list here of the first 1000

http://primes.utm.edu/lists/small/1000.txt

Posted on May 07, 2014

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Posted on Jan 02, 2017

No, 91 is not a prime number, it is a composite number.

Why 91 is not a prime number...

It is Because 91 has divisors rather than 1 and itself. 91 can be divided by 7 and 13.

Why 91 is not a prime number...

It is Because 91 has divisors rather than 1 and itself. 91 can be divided by 7 and 13.

Jul 19, 2017 | Prime Computers & Internet

No it isn't as 1,2,4,8 can be used to divide it prime's are only dividable by 1 or itself only

20 is 1,2,4,5,10

20 is 1,2,4,5,10

Jan 23, 2017 | The Computers & Internet

Hi

Here we go

52 - can be divided by 2 - therefore NOT Prime

63 - can be divided by 3 - therefore NOT Prime

75 - can be divided by 5 - therefore NOT Prime

31 - cannot be divided by whole numbers - therefore Prime

77 - can be divided by 7 - therefore NOT Prime

59 - cannot be divided by whole numbers - therefore Prime

87 - cannot be divided by whole numbers - therefore*Prime*

Hope this is helpful, if so would you please register that with Fixya

Cheers

Here we go

52 - can be divided by 2 - therefore NOT Prime

63 - can be divided by 3 - therefore NOT Prime

75 - can be divided by 5 - therefore NOT Prime

31 - cannot be divided by whole numbers - therefore Prime

77 - can be divided by 7 - therefore NOT Prime

59 - cannot be divided by whole numbers - therefore Prime

87 - cannot be divided by whole numbers - therefore

Hope this is helpful, if so would you please register that with Fixya

Cheers

Mar 08, 2015 | Computers & Internet

One trick I use is to add up all the digits and divide by 3. If the answer is even, (a multiple of 3), it's not a prime number.

57 = 5+7=12. 12 divides by 3 evenly (4), is not a prime.

59 = 5+9=14. 14 does not divide by 3 evenly, therefore prime.

999 = 9+9+9=27 divide by 3 = 9, not prime

997 = 9+9+7=25 divide by 3=8.3 not even and is prime

57 = 5+7=12. 12 divides by 3 evenly (4), is not a prime.

59 = 5+9=14. 14 does not divide by 3 evenly, therefore prime.

999 = 9+9+9=27 divide by 3 = 9, not prime

997 = 9+9+7=25 divide by 3=8.3 not even and is prime

May 30, 2014 | Computers & Internet

There is nothing you can do to make the calculator find the HCF for you. No point complaining about that. But if you are interested in doing it by hand (using the calculator to do the divisions for you) here how it is done.

**Example: **Here are the decompositions of two numbers

(2^5)*3***(5^4)**(7^3)***11** and **(2^3)***(5^6)*(11^2)***7**

The prime factors that are present in both decompositions are

2, 5, 7, and 11

From the two decompositions select the smallest power of each common prime factor. They are represented in** bold font**s.

2^3, 5^4, 7, 11

The highest common divisor/Highest common factor is

**(2^3)*(5^4)*7*11**

- Decompose the first number in prime factors. If a prime factor is repeated use the exponent notation:
**That helps.** **D**ecompose the second number in prime factors too, using the exponent notation.- Now look at the two decompositions. If a prime factor
**is present in both decompositions**it must be in the HCD /HCF, with the smallest of its two exponents. - Do that for all prime factors

(2^5)*3*

The prime factors that are present in both decompositions are

2, 5, 7, and 11

From the two decompositions select the smallest power of each common prime factor. They are represented in

2^3, 5^4, 7, 11

The highest common divisor/Highest common factor is

Mar 27, 2014 | Casio Office Equipment & Supplies

A prime number is a positive whole number (natural number) which cannot be divided into smaller whole numbers. In short, it can only be divided (integer division) by itself and 1.

First prime number is 2, then 3, 5, 7, 11, 13, 17, 19,

To generate a list of prime numbers the Greek Eratoshenes used a method called now the sieve Eratosthenes.

**all subsequent prime numbers**. If it is not divisible by any prime number, keep going but do not exceed the prime number that is closest yet smaller than square root of your number.

Enjoy.

First prime number is 2, then 3, 5, 7, 11, 13, 17, 19,

To generate a list of prime numbers the Greek Eratoshenes used a method called now the sieve Eratosthenes.

- Write all the natural numbers up to some chosen limit (100, 259, any limit )
- Remove 1 by crossing it ( 1 is no longer considered prime).
- The first prime number is 2.
**Circle the number 2.** - Go through the
**whole list**crossing out all the numbers that are multiple of 2, that is 4, 6, 8,10,12, ... - Repeat.
- The next prime number is 3 since it was not crossed out as a multiple of 2.
**Circle 3.** - Go through the
**whole list**crossing all the numbers that are multiples of 3, and which have not already been crossed out as multiples of 2 . - Number 4 has been crossed out already.
- Next prime number is 5.
**Circle 5** - Go through the
**whole list**crossing all the numbers that are multiple of 5 and which have not been crossed out already as multiples of 2, or 3 - Repeat:
- Next prime number is 7.
**Circle 7** **Go through the whole list again, crossing out the multiples of 7, and so on.**

Enjoy.

Nov 26, 2013 | Office Equipment & Supplies

Are you serious?

Oct 12, 2013 | Panini Maurice Jones-drew 2011 Prestige...

3 is a prime number because it cannot be divided evenly by any whole number other than 1 and itself. A prime number is any whole number which cannot be divided evenly by any whole number other than one and itself.

Oct 02, 2013 | Panini Maurice Jones-drew 2011 Prestige...

Prime numbers are those numbers (greater than 1) that cannot be divided by any
number except themselves and one.

The Greek Eratosthenes created a method to find out these prime numbers, although it only worked over a limited range:

1) Write out the numbers from 1 to 100 in ten rows of 10.

The Greek Eratosthenes created a method to find out these prime numbers, although it only worked over a limited range:

1) Write out the numbers from 1 to 100 in ten rows of 10.

2) Cross off number 1, because all primes are greater than 1.

3) Number 2 is a prime, so we can keep it, but we need to cross off the multiples
of 2 (i.e. even numbers).

4) Number 3 is also a prime, so again we keep it and cross off the multiples
of 3.

5) The next number left is 5 (because four has been crossed off), so we keep
it and cross of the multiples of this number.

6) The final number left in the first row is number 7, so cross off its multiples.

7) You have finished. All of the "surviving" numbers (coloured in
white below) on your grid are prime numbers.

Oct 23, 2011 | MathRescue Word Problems Of Algebra Lite

You may want COUNTIF if you're specifying criteria. For instance, if my prices are found in b3 to b7, here's a formula that will find all those that are less than 6 ($6.00):

=COUNTIF(B3:B7, "<6")

If you're using multiple criteria, such as you want to find all the prices that are greater than $5 and less than $8, the following will accomplish it. (The ABS gives you the absolute value of the result, in case the smaller number is first.)

=ABS(SUM(COUNTIF(B3:B7, ">5") - COUNTIF(B3:B7, "<8")))

=COUNTIF(B3:B7, "<6")

If you're using multiple criteria, such as you want to find all the prices that are greater than $5 and less than $8, the following will accomplish it. (The ABS gives you the absolute value of the result, in case the smaller number is first.)

=ABS(SUM(COUNTIF(B3:B7, ">5") - COUNTIF(B3:B7, "<8")))

Nov 06, 2007 | Oracle 10g Database Standard (ODBSEONUPP0)

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