document.getElementById('ask_form').onsubmit = function(e) {
    var expr = document.getElementById('answers_ask_field').value.replace(',','')
    var regex = /^( |\d|\.|\*|\+|\/|-|\(|\))*$/;
    if (expr.match(regex)) {
        try {
            var result = eval(expr);
            if (result !== NaN) {
                e.preventDefault();
                location = wgServer + wgArticlePath.replace('$1',expr);
                return false;
            }
        } catch(err) { return askQuestion() }
    } else { return askQuestion() }
};