finding modulus of huge numbers in java -

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this question has answer here:

      for(i=0; i<n+1; i++)         {             y=y+(a[i]*(int)math.pow(j,i));         }         int r=y/786433;         s[k]=y-(r*786433);         k++;

now in code j value can 786432. when try modulus of number (1+2*(786432)^2+3*(786432)^3)%786433 -521562 not correct using modulus operator before got same answer approach getting same answer. in approach modulus of number stored in array s[k]. can help?

if use math.pow using double types. convert int. rounding can happen , truncating if values big.

to solve problem need use biginteger:

immutable arbitrary-precision integers

in particular method mod:

returns biginteger value (this mod m). method differs remainder in returns non-negative biginteger.


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