Question

How many integers between 2 and 61 are prime numbers inclusive?

Answer 1

"Prime" redirects here. For other uses, see Prime (disambiguation). Demonstration, with Cuisenaire rods, that the number 7 is prime, being divisible only by 1 and 7 A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself. A natural number greater than 1 that is not a prime number is called a composite number. For example, 5 is prime because 1 and 5 are its only positive integer factors, whereas 6 is composite because it has the divisors 2 and 3 in addition to 1 and 6. The fundamental theorem of arithmetic establishes the central role of primes in number theory: any integer greater than 1 is either a prime itself or can be expressed as a product of primes that is unique up to ordering. The uniqueness in this theorem requires excluding 1 as a prime because one can include arbitrarily many instances of 1 in any factorization, e.g., 3, 1 · 3, 1 · 1 · 3, etc. are all valid factorizations of 3.

Answer 2

The prime numbers from 2 to 61, inclusive, are
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, and 61

That's 18 numbers total (you can do the counting to check).

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