"Ugh, it's only 5.7333 o'clock in the morning, I don't want
to get up."
Numbers are everywhere. Seriously, there's no getting away from them. They come in several different forms—whole numbers, fractions, percentages, and so on. We encounter them from the moment we get up until the moment we go to sleep at night. (And sometimes we might even dream about them, which—unless you're an accountant—is pretty weird.)
Don't you hate it when your alarm clock wakes you in the morning when all you want is a few more minutes of sleep? Numbers (and possibly your parents) tell you when it's time to get up. When you're reading the back of your cereal box at the breakfast table, numbers tell you what percent of your daily value of fiber you're getting. Those "All Items ½ Off" signs you see when you go shopping tell you that prices are slashed in half.
Decimals are another way to represent numbers. In fact, we probably see decimals more often on a daily basis than any other type of number. Every time you buy something, or even just look at a price tag, you're looking at decimals. Whenever you turn on the radio, the FM stations are all given as decimals. Ever look up directions on Google Maps? The distance from point A to point B is usually given in decimal form. If you asked Usain Bolt about decimals, he would tell you that all of his times running the 100-yard dash are given in decimal form. (Or, he'd be like, "I'm Usain Bolt, why are you asking me about decimals?" And then he'd run away and we'd never catch him.)
The point (pun intended) is that we see decimals everywhere in our daily lives. How exactly do decimals work? How are they related to other types of numbers, like fractions and percentages? All this and more, right after this commercial break!
Just kidding. We don't do commercials.
- We'll learn what decimals are. Spoiler alert: you probably already know what they are. If you've ever had any interaction with money, you should already be familiar with decimals. But just in case, we've got you covered.
- Decimals and fractions are related to each other, as we'll find out. So, we'll learn how to convert decimals into fractions. It's almost like playing with Transformers, except there are more numbers and fewer explosions.
- Since we love arithmetic, we're going to learn how to add and subtract decimals. Not just simple decimals, but all decimals, including decimals of different lengths. We don't do things the lazy way around here. If we're going to add and subtract decimals, then by golly, we're going to be thorough.
- We won't just stop at addition and subtraction, oh no—we're also going to learn how to multiply and divide decimals. It's a bit tricky, but it's almost the same as multiplying and dividing whole numbers. Almost.
- We're also going to learn about converting between decimals, fractions and percents, oh my!
- To finish things off, we're going to complete a real-world activity to see how we can use our knowledge of decimals in the business world. Time to get creative and show off your newfound math skills!
By the end of this unit, you should know and be able to
- convert decimals into fractions. If you know your decimal places and your powers of ten, this will be a snap.
- add and subtract simple decimals, as well as decimals that go out to different place values. There's no need to sweat the simple stuff. The more challenging stuff will partly require you to tack on a few extra zeros to a number. Yes, you can do that.
- multiply and divide simple decimals with whole numbers, with other simple decimals, and with decimals that go out to different place values. A bit tricky because you'll need to keep track of how many decimal places there are. Don't worry, you'll get the hang of it.
- convert between decimals, fractions, and percents. They're all related to each other, and we're going to figure out how.
- understand and describe real-world situations that require the use of decimals. If you stop and think for a few moments, you can probably already name a couple of situations off the top of your head. We'll look at some other situations in this unit.