Excel formulas for checking contents within a cell.?

I have an Excel SS with sizes of steel tubing in one cell (i.e. 10 X 10 X 1/2, 2 X 3 X 1/8, etc.). I want to Excel to "view" the contents of this cell and place a decimal value in another cell. Example - If the size is 10 X 10 X 1/2 I want Excel to determine the 1/2 at the end of the size and place a ".500" in the other defined cell (Gauge). If the size is 2 X 3 X 1/8 I want Excel to determine the 1/8 at the end of the size and place a ".125" in the other defined cell (Gauge). I have included part of my spreadsheet for review. Any help would be greatly appreciated. Thank you.