Composite Numbers

30 is composite.

Yes, all whole numbers ending in five (except the number five itself) are composite.

Because they have two or more factors but 2 is a prime number because it has only two factors which are itself and one

composite

17, 19, 23, 29 and 31 are prime.

15, 21, 25 and 27 are composite..

The first eight composite numbers are 4, 6, 8, 9, 10, 12, 14, and 15.

A composite number is any number that has more than two factors

Only two numbers fit that category: zero and one.

Public key encryption is based on composite numbers. In fact it is based on composite numbers which are the product of two very large prime numbers.

114 through 126 are all composite.

It is composte because it has more than two factors

An example - the divisors of 28 are 1 -2 - 4 - 7 - 14 and 28. In other words 1+2+4+7+14 = 28

4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, 30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100

what is the ratio or prime numbers to composite numbers in this list/10,11,2,13,14,15,16,1,7,18,19,20,21

1, 2, 3, 4, 9, 12, 18, 36

Eight numbers

120

Yes But Make Sure Its Prime1

249 is a composite number. A prime number has only 2 factors which are 1 and itself. Composite numbers are everything else except 1 and 0. 1 and 0 are neither prime, nor composite.

11 is a prime number. Multiples of 11 greater than 11 are composite. Composite multiples of 11 in that range are 22, 33, 44, 55, 66 and just keep adding 11 till you get to 396.

625 is not prime. 625 = 5 * 5 * 5 * 5

Lets see if 217 is a prime or composite number. 15 times 15 is 225, so we will try the first prime numbers up to 15. They are 2, 3, 5, 7, 11, and 13. Will 2 go into 217? No 7 is odd. Will 3 go into 217. If we add the integers, they add up to 10. 3 does not go into 10. Will 5 go into 217. No. It does not end in a 0 or a 5. Will 7 go into 217. Lets see. Will 7 go into 21? Yes it goes in an even number of times. How about that. Will seven go into 7. Yes it goes in an even number of times. You can show the math.

20, 21, 22, 24, 25

It is 44.

The reason is that 44 = 11 X 4

and 11 + 4 =15.

4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, 30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100, 102, 104, 105, 106, 108, 110, 111, 112, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 128, 129, 130

25, 26, 27, 28, 30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70