 In this video I'm going to talk about a kind of a consumer application for using this type of mathematics. We're going to use, in this video, we're going to use mental math to find a 15% tip for a $34.50 restaurant check. One of the things that you can do here is use a little bit of mathematics to very easily and very quickly figure out percentages. Actually what we're going to be using here is we're going to be using the distributive property to figure out this percentage tip for a restaurant check. First thing we're going to do is get an understanding of this 15%. One thing you can do with 15% is you don't look at it as just 15%, you can look at it as multiple percent, you can look at it as 10% plus 5%. What we did is we took the 15, you kind of split it up into a 5% and a 10%. What this does is this actually makes your math, even though you're splitting it up into what looks like two different problems, it actually makes the math a lot easier because it's a lot easier to find 10% of an item as opposed to 15% of an item. Once you find 10% of an item, then actually finding 5% is relatively easy. What we want to do first is the $34.50 check. We want to find 10% of this. Let me move things over just a little bit. Let's take this, move this over. Come on, there it goes. We want to find, get my pen back here, having troubles. There we go. What I want to do is I want to find 10% of $34.50. If you remember from your basic percentages, to find 10% of something, all you have to do is just move the decimal place once to the left. Actually, 10% of $34.50 is going to be $3.45. Just moving the decimal place once to the left, this zero is going to drop and I got $3.45. That's 10% right there. 5% of $34.50. Now that you might think, oh, Craig, I got to get out of calculator. I got to worry about that. Not necessarily. If we know what 10% is, to find 5%, all we got to do is just find half of that. Half of that is going to be $1.70, just quick mental math here, $1.725. The thing is here, one thing you got to worry about here is if you have this third decimal here with money, you only have two decimals. With this third decimal, what we're going to do is we're going to make that 1.73. Just rounding to make the math just a little bit easier. Now what we have here is we have a $3.45. That's for the 10%, and then we have a $1.73 for the 5%. You can very quickly add these together in your head to figure that out. The 3 and the 1 is going to make 4, but then you also notice here that the 7 and 4 is going to make 11. I was going to bump this one up just a little bit. That's actually going to be a $5.18 for the tip. There we go. Using just a little bit of mental math, not even worry about adding, subtracting, multiplying, dividing, not doing a lot of stuff in our head. We were able to figure out the tip for this restaurant. If I wanted to do a 15% tip, I would throw down $5, $5.25, something to that effect from my weight staff. All right. That is a practical application. It's a consumer application of this type of mathematics using the distributive property. Notice what we did here, a little bit more apparent for distributive property. We're finding 15% of $34.50. What it did is take the 15, take the 15 and split it up into 10 and 5s. Take 34 times 10% and 34.50 times 5%, which is the math that we did over here. All this is what we did over here. Just making it a little bit more blatantly apparent of what we did. We did use the distributive property to do this. That is my consumer application. Hopefully, this video was of some help.