if (this.signum() == 0 || b < 2 || b > 36) return "0";
        var cs = this.chunkSize(b);
        var a = Math.pow(b, cs);
        var d = nbv(a), y = nbi(), z = nbi(), r = "";
        this.divRemTo(d, y, z);
        while (y.signum() > 0) {
            r = (a + z.intValue()).toString(b).substr(1) + r;
            y.divRemTo(d, y, z);
        }
        return z.intValue().toString(b) + r;
    }

// (protected) convert from radix string
    function bnpFromRadix(s, b) {
        var self = this;
        self