<script>
    function calc(str) {
        var otiyot = 'אבגדהוזחטיכלמנסעפצקרשתךםןףץ';
        var values = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 20, 40, 50, 80, 90];
        var res = 0;
        for (var i = 0; i < str.length; i++)
            for (var j = 0; j < 27; j++)
                if (str[i] == otiyot[j])
                    res += values[j];
        document.getElementById('result').innerText = res;
    }
</script>
<body style="text-align: center; background-color: lightcyan;" dir="rtl">
    <p>בסיעתא דשמיא</p>
    <input oninput="calc(this.value)" style="margin-top: 30px;">
    <p id="result" style="font-size: x-large;">0</p>
</body>