Transcripts for the above video clip:

The ISNUMBER function allows you to check whether a cell contains a number or not. So for example if we want to use the ISNUMBER function, we activate the function wizard, we find it, say ok. And you'll see you only have to just point at the cell where you're trying to check, & we say ok. You'll see in this case it tells us that that is a number so it's true. And the benefit is if I copy this down, you'll see it looks & it says true. If there's an error message, for example a divide by zero message, it will then identify that there's a false. So you can build some sort of a check to say, if there's an error, tell me something or do something. Typical example would be equals if that equals true, then we just want to show whatever numbers there. If it equals false, then for example we put a zero. And now when we copy & paste that down, you'll see it automatically looks, & if it's an error it'll then put a zero otherwise it'll actually bring the number through , which just actually helps to avoid errors that creep into models & filter through all the calculations.