St1, Br1, and Wo1 are references to the textbooks. If you want to add the values inside those textboxes, you should do it like this:
function changeInput(){
var calc = parseInt(St1.value) + parseInt(Br1.value) + parseInt(Wo1.value);
Le1.value = calc;
}
1
solved Simple math in HTML enter three values and get result after last value entered