Im using Oraclize to get a random number but the N of bytes confuses me

It seems like when I give the Oraclize query a N of 4, it always returns a 19 digit number, this might be a coincidence but I think not. What if I actually want a number between lets say 0 and 10 * 10^18?

Is this possible? This is how how my Oraclize looks now:

    oraclize_setProof(proofType_Ledger); // sets the Ledger authenticity proof
    uint N = 4; // number of random bytes we want the datasource to return
    uint delay = 0; // number of seconds to wait before the execution takes place
    uint callbackGas = 200000; // amount of gas we want Oraclize to set for the callback function
    bytes32 queryId = oraclize_newRandomDSQuery(delay, N, callbackGas);

And in the __callBack

        uint maxRange = totalEth -1; // deduct one so that when one gets added later it cant be bigger than the total eth.
        randomNumber = (uint(sha3(_result)) % maxRange) + 1 // this is an efficient way to get the uint out in the [1, maxRange] range