Hi I am studying for an exam and having some problems solving one of the questions. It reads as follows: Factor $$N=44370047$$ using Quadratic Sieve by using the information that you get from squaring the following numbers modulo N.

$$33965, 2145407, 19416874, 15213395$$

I know how the algorithm works, i.e $$19416874^2\mod 44370047 = 9 = 3^2$$

And then calculating $$gcd(19416874-3,44370047)$$

I can do this using the computer easily but I have no idea how to calculate the modulo of numbers of this size by hand. Any help would be greatly appreciated as I am currently banging my head against the wall.

  • 2
    $\begingroup$ The basic long division algorithm yields quotient and remainder, does this not fit your needs? $\endgroup$
    – yyyyyyy
    Apr 11, 2017 at 21:09

1 Answer 1


You probably know the algorithms to multiply and divide numbers by hand; that's what you do. Yes, it will be painful. No, there's no other way, but I don't think you will be expected to do it in an exam (confirm that with your instructor, however).


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