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.
2. Multiply the square footage by the height of the ceiling to determine the total cubic footage of the space to be heated. For an average ceiling height of 8 feet and a square footage of 480, the calculation would be 8 x 480 = 3,840 cubic feet.