Rounding to the nearest tenth and hundredth

Joey used 0.432 lbs of cheese to make mac and cheese for dinner. We could also call this 432,000 pounds of cheese to make mac and cheese for dinner. Round the amount of cheese to the nearest tenth.

So, the amount of cheese, once again, is 0.432 lbs. Just remember the places here. This is going to be, this is 410, so that's the tenths place, this is the hundreds place, and that's an S there. So, tenths, hundredths, and this right over here is the thousand thousand place.

So, we want to round to the nearest tenth. We're going to round to the nearest tenth. We go one place to the right; if it's five or larger, we round up. This would become a five. If it's less than five, which is the case here, we're going to round down to just 410 even. Because three is less than five, we are going to round down, and we're going to get 0.4, or we could write that as 0.4, or we could write that as 4/10 of a pound.

Let's do another one. Eliza's pet snail traveled 2.97 meters in one day. Round the distance to the nearest hundredth. So, pause this video and see if you can do that: round the distance to the nearest hundredth.

So, it's 2.97. This is the hundredth place right over here. If we're going to round to the nearest hundredth, we're going to go one place to the right. If this one place to the right is five or greater, we're going to round up, and seven is five or greater, so we are going to round up.

Now, this is interesting because if you round a nine up, you get to 10, but you can't put a whole 10 right over here. So, one way to think about it is we have a 19 here, and if you round up, you're going to go to a 20.

Another way to think about it: if you round the nine up, you're going to go to the next tenth. So, this is going to be 2. We have, you could say, you could view this as 1900 or 1900s and 7,000. So now we're going to round up to 20 hundredths. So, 2.20.

We're rounding to the nearest hundredth, which you could write as 2.2, but to make it clear that you're rounding to the nearest hundredth, you're going to write 2.20. Later in your life, this actually might matter to show how much, to actually show what you're rounding to.

Let's do another example here. Cassandra spends 6.75 hours each day at school. Round the amount of time to the nearest hour. All right, so 6.75. You might be a little confused, and actually, I encourage you to pause the video again and try to solve it on your own.

So, you might be a little confused because they're not saying round it to the nearest tenth or hundredth or one or ten or hundred; they're saying to the nearest hour. But in this case, the hour is the one's place, so if we're going to round to the nearest hour, this is another way of saying round to the nearest one.

So, we're going to round to the nearest one. We go one place to the right; we go to look at the tenth place. If it's five or larger, we round up. Well, seven is five or larger, so we round up to the next hour, which is going to be seven.

So, it's 7 hours. If this was 6.49, once again, if we're rounding to the nearest hour, we go one place to the right. It doesn't matter that we have all these nines here. We'd say, “Hey, look, four is less than five; therefore, we should round down.” Round down, and you would round down to the next hour.

Well, the next hour that's below 6.49 is 6 hours. But in this case, we had a seven in the tenth place, which is definitely greater than or equal to five. So, we round up to the next hour, which is 7 hours.