Drop down box with dollar amounts

I have a selection box with certain currency amounts in it. I need to perform a numerical calculation on the chosen amount, but it seems I am unable, perhaps because it’s a selection and not specifically numeric. I tried to read the data from it to a numeric field so I could use it…to no avail. any way around this limitation? TIA!

Selection option with $ could be harder to process. You will need to do something like this to trim out the dollar sign:


and if you need to convert it into a number for a numeric field, do it like this when necessary: