Prime numbers are integers, greater than 1, only divisible by themselves and 1 (e.g. 7 and 13)
Composite numbers are also integers greater than 1, which can be divided by at least one other factor, save themselves and 1 (e.g. 50 divides by 50 and 1, but also 25, 2, 5 and 10)
The factors of 34: 34, 1, 17, 2 Of these:
2 and 17 are prime
34 is composite (it divides by 17 and 2 as well as itself and 1)
1 is neither prime nor composite, because it is not greater than 1
The factors of 72: 72, 1, 36, 2, 24, 3, 18, 4, 12, 6, 9, 8 Of these:
2 and 3 are prime
72, 36, 24, 18, 4, 12, 6, 9 and 8 are composite
1 is neither prime nor composite, because it is not greater than 1
For the sake of interest, 6 is a special type of number known as a perfect number. This is because it is equal to the sum of all its integer factors (except for 6 of course!): 1 + 2 + 3 = 6. The next is 28, then 496, then 8128. After this, they become extremely large, because they become increasingly uncommon as you keep counting upwards...
The factors of 34 are 1, 2, 17, and 34, with 2 and 17 as prime and 34 as composite. The factors of 72 are 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, and 72, with 2 and 3 as prime and 4, 6, 8, 9, 12, 18, 24, 36, and 72 as composite. The number 1 is neither prime nor composite.
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