Most spreadsheet applications have built in formulas and functions that will do the math for you so you don't have to. You can keep a running balance of your accounts and you can have each category totaled as well. You can keep it as simple or make it as sophisticated as you please.
When VisiCalc hit the scene back in the eighties (in the last century), the relatively small group of Apple II users went crazy. It was like manna from heaven for the poor accountants, scientists and engineers who were used to filling in enormous analysis sheets with a pencil. Now, they could use VisiCalc to do the same task, AND calculate the result automatically.
Financial templates are highly complex and they deal with very large and advanced calculations. These spreadsheets are used in mortgage, loans, and property investments and so on.
Once you design the type of budgeting spreadsheets you want to use, it will be easy to copy it for subsequent months or years. You can also use just one sheet and create tabs for each month.
examples of spreadsheet packages
excel inventory templates