When you are working with large data sets, making drop down menus can qualify the data entered, which will greatly decrease the error rate of input data. Furthermore, if you want to know what is repeated in a set of data, counting one by one is troublesome, the highlight duplicates function may help you. To use these two functions, follow the steps as below:

Make drop down menus
Step 1. Select the data area you want to fill in.

Step 2. Choose the “Data” tab of the top menu, click Validation, and you will see the Data Validation dialogue box.

Step 3. Choose the “List” for Allow, and in the Source box, you could enter “One,Two,Three,Four,Five,Six” or you can enter what you want to use in some other cells, and use the mouse to select this data area.

Step 4. Press the “OK” button to complete, and you will see the button on the right of every table cell. Click it to choose any of them to fill in the cell.