HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010

We can now test to see if this is a prime number by using the

ISPRIME?

function from the

MATH menu. This is found in the Integer section of the

CAS function list as shown right.

It returns a value of

0 (false) indicating that it is not a prime number.

Using the

FACTOR function from the menu shows that its factors

are 641 and 6700417.

Note: The

ISPRIME? function gives correct results for integers up to

Beyond that level the results are highly probable to be

correct but not guaranteed. They are obtained using “Rabin’s

Algorithm” and are called ‘pseudo primes’.

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