Question Video: Ordering 9-Digit Numbers

In 2019, the population of the United States of America was 329,991,000; that of Brazil was 210,511,000; and that of Indonesia was 268,074,600. Order the three populations from least to greatest.

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Video Transcript

In 2019, the population of the United States of America was 329,991,000. That of Brazil was 210,511,000. And that of Indonesia was 268,074,600. Order the three populations from least to greatest.

Any country’s population or the number of people that live there is often a large number. And here we have three countries that have a nine-digit number that shows their population. We’re given the population of the United States, that of Brazil, and also Indonesia. And we’re asked to order these three populations from least to greatest.

Now we could try to compare these three numbers by looking across at them as they’re written at the moment in part of a sentence. But when we’re comparing large numbers with lots of digits, it often helps to write them out vertically, in other words one number on top of another. This way, we can compare the value of each digit one by one.

Now a nine-digit number is written in three groups of three digits, with a comma separating them. Going from right to left, we have our ones, tens, and hundreds digits. And we can call this group of three the ones. Our next group of three digits we could call our thousands digits. If we keep going from right to left, we have our thousands, ten thousands, and hundred thousands places. And in between our thousands and ones groups, we have a comma to separate them. This helps us to read the number more quickly.

Our final group of three digits is our millions group. And the three-digit places are worth millions, ten millions, and hundred millions. And again, there’s a comma between our millions and thousands groups to help us read the number.

Now we’ve drawn the place value grid. We can write out each population. In 2019, the population of the United States of America was 329,991,000. We’re told that Brazil’s population was 210,511,000. And finally, the population of Indonesia was 268,074,600.

Now that we’ve set out these large numbers vertically and we’ve got the place value grid to help us, we can compare them quickly. A lot more quickly than looking around from one number to another in a sentence. So should we start by looking at the ones place and then the tens? No. If we start with the ones place, we’re starting with a digit that has least value. Whether any of these populations have nine ones or eight ones or even one one, it doesn’t matter.

To begin with, we need to be comparing the digits that have the greatest value. These are the ones that are most important in our numbers. And the digits with the greatest value are our hundred millions digits. If we spend a moment to look at these, we can see that two of our populations contain the digit two in the hundred millions place. One of them contains the digit three. So although we might not know at this point which population is the least, we can certainly say which one is the greatest of our three populations. It’s the United States. It has the greatest digit in the place with the greatest value.

We need to write our three numbers in order from least to greatest, so we know which the third number in our list is going to be. It’s going to be the population of the United States, which is 329,991,000.

We now need to put the other two populations in order. Will they come first or second in our list? We can’t separate these two numbers by looking at the hundred millions digits. So now we have to look at the digit with the next largest value. This is the ten millions place. One of our numbers has 10 millions with a one in this place, and the other has 60 millions, with a six in the ten millions place. One is less than six. So we can say that the first number and the least out of our three numbers is the population of Brazil. This means then that the second number in our list must be the population of Indonesia.

We compared these three nine-digit numbers by using a place value grid to help. We put them in order from least to greatest by looking at the digits that had the greatest value first. In order then from least to greatest, the populations are Brazil then Indonesia then the United States of America. And these numbers are 210,511,000, 268,074,600, and 329,991,000.

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