Javascript multiplication question

Can someone tell me why this number does not come out? If I multiply it by 1000, the answer is correct.

Please help.

— Jackie

var first_num = 1.15;
var second_num = 100;
var result = first_num * second_num;

document.writeln(first_num);
document.writeln(” * “);
document.writeln(second_num);
document.writeln(” = “);
document.writeln(result);