Blood Type Compatibility. Your ABO blood type is based on the presence or absence of the A and B antigens on your red blood cells. The A blood type has only the A antigen and the B blood type has only the B antigen. The AB blood type has both A and B antigens, and the O blood type has neither A nor B antigen.
Green Triangle. The green triangle appears in the upper left hand corner of a cell when there is an error in a formula. Sometimes Excel will report an error when you use text in a box and the program believes it is part of a formula. When you click on the green triangle there will be a yellow box that looks like a road sign with an exclamation point in it. This button is the Trace Error option that will help you correct your formula.
Subtracting Within a Cell. 1  1. Open Excel. It's a green app with a white X on it. 2  2. Click Blank workbook (PC) or Excel Workbook (Mac). It's in the top-left side of the Template window. 3  3. Click a cell. Unless you plan on creating data using this workbook, the cell you select is not important.  4. Type = into the cell.