The sign for less than is <. Here is an example of how it is used: 3 < 5. It is a boolean operator, which means that it is used to make a comparison between two numbers. In programming, if 3 < 5 was stored in a boolean variable, then the variable would have a value of ‘True’ or 1 because this is a true statement. On the other hand, 5 < 3 would return ‘False’ or 0 because that statment is untrue.