39 = 3 x 13
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No, 39 is not prime.
To find the GCF of 13 and 39, you can list the factors of each number. The factors of 13 are 1, 13. The factors of 39 are 1, 3, 13, 39. 13 is the GCF of 13 and 39. 3 is a prime number has only two factors: 1 and 13. 13 will divide into 39 three times. Since 13 is a prime number that will divide into 39, it has to be the GCF of 13 and 39.
Yes, 390 is a composite number. It has factors other than 1 and 390. The factors of 390 are 1, 2, 3, 5, 6, 10, 13, 15, 26, 30, 39, 65, 78, 130, 195, and 390.
A composite number is a positive integer which has a positive divisor other than one or itself. In other words, if n > 0 is an integer and there are integers 1 < a, b < n such that n = a × b, then n is composite. By definition, every integer greater than one is either a prime number or a composite number. The number one is a unit - it is neither prime nor composite. For example, the integer 14 is a composite number because it can be factored as 2 × 7. Likewise, the integers 2 and 3 are not composite numbers because each of them can only be divided by one and itself.The first 105 composite numbers are: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, 132, 133, 134, 135, 136, 138, 140.
The factors of 117 are 1,3,9,13,39,and 117The factors of 117 are 1, 3, 9, 13, 39, and 117.1,3,9,13,39,and 1171x117;3x39;9x13To find the factors of a number, it is helpful to know the rules for checking if something is a divisor. One rule is that if a numbers digits add up to 9, the number divides by 9. In this case, 117 has digits which add up to 9, and so can be divided by 9. If we do this, we get 13, which is prime. Thus the prime factors are 3, 3 and 13. These can be combined to get the other factors. Therefore the factors of 117 are 1, 3, 9, 13, 39 and 117.