Variable length list input

Question

I'm writing a wasm statistical calculator, so I need to allow an arbitrarily long number input on my website's front end. My current design looks like this:

A number is entered where the line is. Enter adds a new number input to the end and focuses it. Emptying an input removes it (and similarly focuses the last element), for instance like below:

The 'calculate' button can be clicked/pressed, and the page logic will take place, outputting results above the input.

How can I improve this such that it takes no instruction to use?

Edit

In case the above description of the current design was confusing, here's a GIF

Answer 1

There are a couple of elements I see rare or unusual in the design:

1. The button moves when adding new numbers, this is totally unusual in interactivity. One of the premises in interactivity is the user must clearly know where to interact, if the interaction field changes places it generates uncertainty.
2. The text insertion line is horizontal, this occurs in coding programs but it's unusual in user interfaces, where the text field is accompanied by the vertical blinking insertion line.

I can think of two basic possibilities, one complete and one with more interactivity. The base is the same for both, a text insertion field, an area with the added quantities, a scroll bar to see the hidden numbers and the operation buttons:

The second has the same elements but is cleaner, favoring the vision of the data:

• Info button shows the tooltip
• Eraser button to reset
• Check button to calculate

Added after the comment

How modification or deletion of an individual element takes place?

To edit an element:

• Click the element to select it
• Tap the Erase Button to delete the content
• Type the new number at the text insertion field

To delete an element:

• Click the element to select it
• Tap twice the Erase Button