I have read about gaussian elimination technique from this link. http://e-maxx-eng.github.io/linear_algebra/linear-system-gauss.html . But how do we solve the equations given a prime modulo? do i need to calculate the multiplicative inverse every time i have to divide the row with a number or is there another way to do that without using multiplicative inverse?

can someone tell me what is wrong with my code? i first generated all the primes up to sqrt(10^7) and then for every prime, counted how many number are divided by it...

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