function main(s, e, bs, pbs) {
    bs = bs || 10;
    pbs = pbs || 10
    document.write('start:', toString(s), ' end:', toString(e),
        ' base:', bs, ' printBase:', pbs)
    document.write('<br>castOutNine: ');
    castOutNine()
    document.write('<br>kaprekar: ');
    kaprekar()
    document.write('<br><br>')

    function castOutNine() {
        for (var n = s, k = 0, bsm1 = bs - 1; n <= e; n += 1)
            if (n % bsm1 == (n * n) % bsm1) k += 1,
                document.write(toString(n), ' ')
        document.write('<br>trying ', k, ' numbers instead of ', n = e - s + 1,
            ' numbers saves ', (100 - k / n * 100)
            .toFixed(3), '%')
    }

    function kaprekar() {
        for (var n = s; n <= e; n += 1)
            if (isKaprekar(n)) document.write(toString(n), ' ')

        function isKaprekar(n) {
            if (n < 1) return false
            if (n == 1) return true
            var s = (n * n)
                .toString(bs)
            for (var i = 1, e = s.length; i < e; i += 1) {
                var a = parseInt(s.substr(0, i), bs)
                var b = parseInt(s.substr(i), bs)
                if (b && a + b == n) return true
            }
            return false
        }
    }

    function toString(n) {
        return n.toString(pbs)
            .toUpperCase()
    }
}
main(1, 10 * 10 - 1)
main(1, 16 * 16 - 1, 16)
main(1, 17 * 17 - 1, 17)
main(parseInt('10', 17), parseInt('gg', 17), 17, 17)