If you are trying to take the formula in XYZ and multiply it against all the cells in a range, make sure the cell references in the formula in XYZ are absolute (use $), copy cell XYZ, then highlight the range of cells you want multiplied then paste special>formulas>multiply
If you want the cells in the range to know have *XYZ added to them, then in a different cell, put =XYZ with absolute references, then copy that cell, highlight the range of cells you want multiplied then paste special>formulas>multiply