JavaScript Javascript .style.display not working

[supasibs]

function addSwitch() {
         let base = document.getElementById("Base");
         let sub = document.getElementById("Subtract");
         let add = document.getElementById("Add");
         let mul = document.getElementById("Multiply");
         let div = document.getElementById("Divide");
          base = base.style.display = "none";
         sub = sub.style.display = "none" ;
         add = add.style.display = "block" ;
         mul = mul.style.display = "none" ;
         div = div.style.display = "none" ;
    }
// So on except the one before the word switch is the one getting block display and
// the rest is display none

Add is supposed to turn block, but it isn't. Dunno how to explain it any other way