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  2. Primality test - Wikipedia

    en.wikipedia.org/wiki/Primality_test

    Primality test. A primality test is an algorithm for determining whether an input number is prime. Among other fields of mathematics, it is used for cryptography. Unlike integer factorization, primality tests do not generally give prime factors, only stating whether the input number is prime or not.

  3. Magic number (programming) - Wikipedia

    en.wikipedia.org/wiki/Magic_number_(programming)

    the use of 2 to check whether a number is even or odd, as in isEven = (x % 2 == 0), where % is the modulo operator; the use of simple arithmetic constants, e.g., in expressions such as circumference = 2 * Math.PI * radius, [1] or for calculating the discriminant of a quadratic equation as d = b^2 − 4*a*c

  4. Divisibility rule - Wikipedia

    en.wikipedia.org/wiki/Divisibility_rule

    92 ÷ 4 = 23 (Check to see if the number is divisible by 4) 2092 ÷ 4 = 523 (If the number that is obtained is divisible by 4, then the original number is divisible by 4) Second method. 6174 (the original number) check that last digit is even, otherwise 6174 can't be divisible by 4. 61 7 4 (Separate the last 2 digits from the rest of the number)

  5. Check digit - Wikipedia

    en.wikipedia.org/wiki/Check_digit

    For instance, the UPC-A barcode for a box of tissues is "036000241457". The last digit is the check digit "7", and if the other numbers are correct then the check digit calculation must produce 7. Add the odd number digits: 0+6+0+2+1+5 = 14. Multiply the result by 3: 14 × 3 = 42. Add the even number digits: 3+0+0+4+4 = 11.

  6. Parity bit - Wikipedia

    en.wikipedia.org/wiki/Parity_bit

    In the case of odd parity, the coding is reversed. For a given set of bits, if the count of bits with a value of 1 is even, the parity bit value is set to 1 making the total count of 1s in the whole set (including the parity bit) an odd number. If the count of bits with a value of 1 is odd, the count is already odd so the parity bit's value is 0.

  7. Sanity check - Wikipedia

    en.wikipedia.org/wiki/Sanity_check

    Sanity check. A sanity check or sanity test is a basic test to quickly evaluate whether a claim or the result of a calculation can possibly be true. It is a simple check to see if the produced material is rational (that the material's creator was thinking rationally, applying sanity). The point of a sanity test is to rule out certain classes of ...

  8. Miller–Rabin primality test - Wikipedia

    en.wikipedia.org/wiki/Miller–Rabin_primality_test

    Input #1: b, the number of bits of the result Input #2: k, the number of rounds of testing to perform Output: a strong probable prime n while True: pick a random odd integer n in the range [2 b−1, 2 b −1] if the Miller–Rabin test with inputs n and k returns “probably prime” then return n

  9. Fermat primality test - Wikipedia

    en.wikipedia.org/wiki/Fermat_primality_test

    Concept. Fermat's little theorem states that if p is prime and a is not divisible by p, then. If one wants to test whether p is prime, then we can pick random integers a not divisible by p and see whether the congruence holds. If it does not hold for a value of a, then p is composite. This congruence is unlikely to hold for a random a if p is ...