Subtraction Formula on Column format Number

[lucas_ignatius]

Hi, Can anybody give me an Idea, how to write formula Subtraction on SharePoint List with Column format Number, because, it can't work and can't save.

Subtraction formula is TotalCategoryBudget - Realisasi. I Need in format column Number, because if with calculated it will be work.

Thanks for everyone who support me.

[#2]

You can't do it with a number column, it needs to be a calculated column.

[#3]

So what function for calculated in there?
And how to add symbol if using calculated column?