Write a code to ask the user about the number of letters sent each day of the week and display the total number of letters sent in a week in console in javascript 

```js
var day = 1;
var totalletters = 0; //total letters sent

for (day; day <= 7; day++) {
  var getletters = 0;
  getletters = prompt("Please enter the number of total letters sent today", );
  totalletters += getletters;
}

console.log(totalletters); //displaying the total number of letters sent at the end of the week

// The console is showing the output as string instead of adding up the numbers
```