To calculate the subtotal amount and sales taxes from a total: 1  Ensure that the Find Subtotal (before tax) tab is selected.  2 Province of Sale - Select the province where the product buyer is located.3  For provinces that split GST from PST (such as Manitoba, Quebec and Saskatchewan) a No PST checkbox will appear.he second tab lets you calculate the taxes from a grand total including tax, and gives you the subtotal before tax. Useful for figuring out sales taxes if you sell products with tax included - or if you want to extract tax amounts from grand totals. 1  Calculator Instructions.
Measuring accurately, and rounding up slightly are the keys to figuring out the square footage of wallpaper needed. This method will give you plenty of wallpaper for matching up patterns, covering unusually shaped areas, and even repairing small mistakes without wasting money and leaving you with excess paper.
MEASURING AREAS. Before you can figure out how much material you require, you will need to calculate square foot measurements (or meters) of the surface area that is being covered. A floor or ceiling can be easy to figure out. Just multiply length times width. As an example, if your living-room is 15 feet long by 20 feet wide the calculation would be 15' x 20' = 300 sq ft of floor or ceiling area. Walls can be a little more difficult to measure, especially, when you're considering decorating an entire room.