Input Restriction with Data Validation Function

In order to retain the validity of data, sometimes you need to restrict the input value and offer some tips for further steps. For example, age in this sheet should be whole numbers and all people participating in this survey should be between 18 and 60 years old. To ensure that data outside of this age range isn’t entered, go to Data->Data Validation->Setting, input the conditions and shift to Input Message to give prompts like, “Please input your age with whole number, which should range from 18 to 60.” Users will get this prompt when hanging the pointer in this area and get a warning message if the inputted information is unqualified.

Ref: http://www.lifehack.org/articles/technology/20-excel-spreadsheet-secrets-youll-never-know-you-dont-read-this.html