 So let's design out a practical application for why we would probably want to do something like this And one of them is say working with currency because if we think about a currency is kind of important Well, if we look at just a traditional English number or currency value say $75.27 let's look at what we're seeing here Currency is going to start with some number then it's going to have some Number of numbers in front of it. It's going to then in turn have a period and then this is kind of important It's gonna have two sets two to two. That's kind of a big issue So what can we do with this? Well, there's a few things that we have to deal with you see the dollar sign is actually a special character inside of regular expressions as The period over here. So we can't just magically make them. I can't just put them into my expression So what can I do? Well first? Let's go ahead and sort of design this out My pattern if we kind of looked at it would be I need to tackle That exclamation that that dollar sign Well, if I run into the problem of a character that I need that is used inside of regular expressions what I need to do is just like when I would work with a Regular an escape character inside of a string. I use the backslash Then whatever I put right after in this case the dollar sign that indicates that I'm not worried about the actual kind of usage Of the dollar sign which means in the document or in the line I'm now talking about the actual character of the dollar sign The next thing I'm dealing with is that I'm gonna have 75 but 75 is not the only possible number I might be dealing with I might also deal with $100 and 0 cents. I might deal with $1 and 75 cents I might deal with a thousand and for our sake will ignore commas So How do I kind of tackle this? Well, I need numbers. I need only numbers So I'm gonna create sort of that same and I'll use the same color I Create a choice That I need to be working off of and I need to work off repeatability Well, we see that in this case. I have two in this case. I have three this case. I have one and in this case I have four so I'm always gonna have at least one Possible number and we'll you know for my kind of pattern So I'll come in here and I'll deal with a plus sign remember the plus sign says that it can be at least one character Now one of the things I'm actually able to do inside of these square braces is I could type out zero one two three four five six Seventy-nine, you know, yes, I can but since sort of regular expressions when they were designed Said, you know, probably people are gonna be saying they're gonna need numbers. We're able to work off of a range Instead I'm able to do something like zero to nine and that's gonna say zero to nine and including everything in between it Now getting back to kind of how we were looking at things. We said that period again It's a special character just like the dollar sign. So it's actually gonna do the same thing It's gonna need to have its backslash in front of it to indicate. This is talking about Just the dollar or sorry just the decimal point Finally we run into These two numbers and I'm gonna use the same approach that I did over here. I'm gonna use square brackets zero dash nine however, one of the things I'm able to do is I'm able to Utilize instead of the plus sign that I did here, which is you know zero one to an infinite number I can limit it with these curly braces and state that only two digits are going to appear