[Hoshinokoe]

notsoft,

Можно.

function schet() {
    var res = 0;

    for (var i = 1; i <= 200; i++) {
        var n = document.getElementsByName("n" + i)[0].value;
        var c = document.getElementsByName("c" + i)[0].value;
        var z = document.getElementsByName("z" + i)[0].value;

        if (!z && z > 0) {
            n = document.getElementsByName("n" + i)[0].value = "";
            c = z = "";
        }

        res += c * z;
    }
    document.getElementById("rezult").innerHTML='<h1>R EZULTAT: '+res +'</h1>';
}