In addition we can say of the number 40 that it is even
40 is an even number, as it is divisible by 2 : 40/2 = 20
The factors for 40 are all the numbers between -40 and 40 , which divide 40 without leaving any remainder. Since 40 divided by -40 is an integer, -40 is a factor of 40 .
Since 40 divided by -40 is a whole number, -40 is a factor of 40
Since 40 divided by -20 is a whole number, -20 is a factor of 40
Since 40 divided by -10 is a whole number, -10 is a factor of 40
Since 40 divided by -8 is a whole number, -8 is a factor of 40
Since 40 divided by -5 is a whole number, -5 is a factor of 40
Since 40 divided by -4 is a whole number, -4 is a factor of 40
Since 40 divided by -2 is a whole number, -2 is a factor of 40
Since 40 divided by -1 is a whole number, -1 is a factor of 40
Multiples of 40 are all integers divisible by 40 , i.e. the remainder of the full division by 40 is zero. There are infinite multiples of 40. The smallest multiples of 40 are:
It is possible to determine using mathematical techniques whether an integer is prime or not.
for 40, the answer is: No, 40 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 40). 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 6.325 ). 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.
Previous prime number: 37
Next prime number: 41