JSFiddle - React, Tailwind, and code Playground

HTML

M = <input type="number" id="id_m" value="6" min="1" max="30"><br />
N = <input type="number" id="id_n" value="5" min="1" max="90"><br />
<input type="button" value="Calc" id="id_c"><br />
<div id="id_r"></div>

CSS

* {
  font-size: 26px;
}
input {
  width: 80px;
}

JavaScript

var calculation = (function() {
    function sumCount(f, m, n, saved) {
        if (m < 2) {
            return n < 10 && n >= f ? 1 : 0;
        }
        if (n < 1) {
            return 1 - f;
        }
        if (saved[m][n] >= 0) {
            return saved[m][n];
        }
        var c = 0, last = Math.min(n, 9);
        for (var i = f; i <= last; ++i) {
            c += sumCount(0, m - 1, n - i, saved);
        }
        return saved[m][n] = c;
    }

    function calc(M, N) {
        var saved = [];
        var digs = Math.ceil(M / 2);
        for (var i = 0; i <= digs; ++i) {
            saved[i] = new Array(N + 1);
            for (var j = 0; j <= N; ++j) {
                saved[i][j] = -1;
            }
        }
        var count = sumCount(M % 2, digs, N, saved);
        var suf = Array(Math.ceil(M / 2)).join('0');
        var k = M % 2 ? 1 : 9;
        
        return count ? (count * k) + suf : '0';
    }

    return calc;
})();


//---------------------------------------------------
document.getElementById("id_c").onclick = function() {

  var M = parseInt(document.getElementById("id_m").value, 10);
  var N = parseInt(document.getElementById("id_n").value, 10);

  document.getElementById("id_r").innerHTML = calculation(M, N);

}