form {
  width: 300px;
  margin: 0 auto;
}

label {
  display: inline-block;
  width: 100px;
  margin-bottom: 10px;
}

input[type="number"] {
  width: 200px;
  height: 30px;
  padding: 5px;
  border-radius: 5px;
  border: 1px solid #ccc;
  margin-bottom: 10px;
}

input[type="button"] {
  width: 100%;
  height: 40px;
  background-color: #008CBA;
  color: #fff;
  border-radius: 5px;
  border: none;
  cursor: pointer;
  margin-bottom: 10px;
}

#result {
  font-size: 20px;
  font-weight: bold;
  margin-top: 20px;
}