Question Video: Ordering Four Masses in Kilograms and Grams from Lightest to Heaviest | Nagwa Question Video: Ordering Four Masses in Kilograms and Grams from Lightest to Heaviest | Nagwa

# Question Video: Ordering Four Masses in Kilograms and Grams from Lightest to Heaviest Mathematics • Fourth Year of Primary School

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Order the given masses indicated on the cards from lightest to heaviest.

05:05

### Video Transcript

Order the given masses indicated on the cards from lightest to heaviest. 1,674 grams, one kilogram 825 grams, 1,324 grams, and one kilogram 647 grams.

We’re given four colored cards here. And on each one, we can see a mass. And the question asks us to order the masses from lightest to heaviest. Now perhaps we’d normally expect if we were looking at some measurements of mass that something that weighs a very small amount might have a small number and something that’s a lot heavier would have a larger number. But there’s a slight problem with thinking like this. Can you see what it is?

The measurements that are written on the cards are not all using the same unit of measurement. We’ve got mixed units. We’ve got two measurements in grams. And then we’ve got two measurements that show a whole number of kilograms and then some more grams on the end. And so if we were just looking at the numbers on the cards, we might say that the blue card shows the smallest numbers and 1,674 is definitely the largest number we can see. But we can’t actually say these are the lightest and heaviest masses. The only way we can compare these measurements together is by converting some of them so that they’re all in the same unit of measurement.

Now there’s two ways we could do this. One way is that we could take these two measurements and convert them from grams into mixed units, so a whole number of kilograms and then some more grams. That way, all the measurements on the cards will be written in kilograms and grams. Or we could leave those two as they are and instead take the red and the blue cards and convert them from mixed units, kilograms and grams, into just a number of grams. And that way, all the cards will be written as so many grams.

Now either of these two methods would work. It doesn’t matter which one we do. But perhaps in this question, we’ll go with the second option. The reason is it’s going to give us one number at the end rather than two. And it’s a bit easier to compare if we just have one large number.

So first of all, let’s take our red card. Let’s convert one kilogram 825 grams into just grams. And as we can see, part of our number is already in grams. We know we already have 825 grams. So we just need to convert our kilograms into grams, too. We know that one kilogram is equal to 1,000 grams. And remembering this fact is really useful because that’s all we need to convert here. We have one kilogram. And so we just need to write 1,000 grams. So the mass on the red card is worth 1,000 grams and another 825 grams. Put the two parts back together. And what have we got? 1,825 grams.

Let’s cross out the mass that’s written at the moment. And we’ll write what it’s worth in grams above. Now we just need to do exactly the same thing with the blue card. At the moment, it reads one kilogram 647 grams. As before, part of it is written in grams already. That’s the 647 grams. And once again, it’s quite quick to convert our kilograms into grams because we’ve only got one of them. That’s 1,000 grams again. And if we add together 1,000 grams and also 647 grams, we have 1,647 grams. So we can cross through these mixed units and write the exact same thing just in grams.

And now that all the masses are in the same units of measurement, we can just look at the numbers. Each number has the same number of thousands, so we’re going to need to move on and look at the hundreds digits. The smallest number of hundreds is on the yellow card. It’s three. So our lightest weight is 1,324 grams. But we can see that the largest digit is eight 100s, so the mass on the red card must be heaviest.

Now what about the two masses in between? Unfortunately, we can’t split them up by looking at the hundreds. They both contain six 100s. So we need to look at the tens digits. And seven 10s on the green card is greater than four 10s on the blue card. So that’s how we know 1,674 grams is greater than one kilogram 647 grams. The masses in order from lightest to heaviest are 1,324 grams, one kilogram 647 grams, 1,674 grams, and one kilogram 825 grams.

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