Type up the values you wish to add up in the column on the left. Each value must be on a separate line.

You can use dots or commas for decimal values, indiscriminately.
If you wish to subtract a value rather than add it, just put a minus sign in the front, e.g: -33

You can add up the values in the list at any time by clicking on the "ADD" button.
(Choose the "Decimal Comma" or "Decimal Point" option previously to determine how the total should be displayed.)
The total will be shown immediately in the box above the button.

If you close the program and then re-open it later, a temporary copy of the addition list you are working on will be retrieved automatically.
If you want to make a permanent copy of the list, then you can use the "Save As" button at the top.
(Whenever you exit the program, you are also given the opportunity to make a permanent copy.)
You can save your addition list files anywhere on your computer. However, if you find it convenient, you can keep your files in the program
folder's sub‑ folder named "addition files".
Addition lists can be loaded from permanent storage using the "OPEN" button. Just navigate to where you stored them.

If you wish to start a new list afresh, use the "NEW" button to clear everything down.