In addition we can say of the number 38 that it is even
38 is an even number, as it is divisible by 2 : 38/2 = 19
The factors for 38 are all the numbers between -38 and 38 , which divide 38 without leaving any remainder. Since 38 divided by -38 is an integer, -38 is a factor of 38 .
Since 38 divided by -38 is a whole number, -38 is a factor of 38
Since 38 divided by -19 is a whole number, -19 is a factor of 38
Since 38 divided by -2 is a whole number, -2 is a factor of 38
Since 38 divided by -1 is a whole number, -1 is a factor of 38
Since 38 divided by 1 is a whole number, 1 is a factor of 38
Since 38 divided by 2 is a whole number, 2 is a factor of 38
Since 38 divided by 19 is a whole number, 19 is a factor of 38
Multiples of 38 are all integers divisible by 38 , i.e. the remainder of the full division by 38 is zero. There are infinite multiples of 38. The smallest multiples of 38 are:
0 : in fact, 0 is divisible by any integer, so it is also a multiple of 38 since 0 × 38 = 0
38 : in fact, 38 is a multiple of itself, since 38 is divisible by 38 (it was 38 / 38 = 1, so the rest of this division is zero)
etc.
It is possible to determine using mathematical techniques whether an integer is prime or not.
for 38, the answer is: No, 38 is not a prime number.
To know the primality of an integer, we can use several algorithms. The most naive is to try all divisors below the number you want to know if it is prime (in our case 38). We can already eliminate even numbers bigger than 2 (then 4 , 6 , 8 ...). Besides, we can stop at the square root of the number in question (here 6.164 ). Historically, the Eratosthenes screen (which dates back to Antiquity) uses this technique relatively effectively.
More modern techniques include the Atkin screen, probabilistic tests, or the cyclotomic test.
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