When you have kidney disease, your kidneys are no longer able to remove waste effectively from your body or to balance your fluids. The build up of wastes can change the chemistry of your body causing some symptoms that you can feel, and others that you don't.
Reference to a range of cells is typically of the form (A1:A6), which specifies all the cells in the range A1 through to A6. A formula such as =SUM(A1:A6) would add all the cells specified and put the result in the cell containing the formula itself.
Excel is trained to look for numbers being entered in cells, not numbers that look like text, like part numbers or SKU's. To retain leading zeros, format the input range as Text before you paste or enter values.