diff --git a/main.js b/main.js
index 32ed12f..d2d02df 100644
--- a/main.js
+++ b/main.js
@@ -55,7 +55,7 @@ function keyPress(c) {
 	const begin = currentInput.value.slice(0, selectionStart);
 	const end = currentInput.value.slice(selectionEnd);
 	currentInput.value = begin + c + end;
-	currentInput.setSelectionRange(selectionStart+1, selectionStart+1);
+	currentInput.setSelectionRange(selectionStart+c.length, selectionStart+c.length);
 }
 
 function backspace() {
@@ -107,10 +107,11 @@ document.querySelector("#lparen").addEventListener("click", () => keyPress("("))
 document.querySelector("#rparen").addEventListener("click", () => keyPress(")"));
 
 document.querySelector("#pow").addEventListener("click", () => keyPress("^"));
+document.querySelector("#inv").addEventListener("click", () => keyPress("^-1"));
 
 document.querySelector("#clear").addEventListener("click", clear);
 document.querySelector("#enter").addEventListener("click", evaluate);
 
 document.querySelector("#backspace").addEventListener("click", backspace);
 
-// TODO implement square root and inverse keys
+// TODO implement square root key