🔢 Millions: Reading Big Numbers

Hello! How many people are in a full stadium? How many kilometres away is the Moon? Today we will learn to read and write really big numbers.

Let’s picture big numbers. Let one square be 10,000 people. 100 squares make 1,000,000 people: one million! That would fill lots of stadiums.

Each place is 10 times the place on its right. 10 ones make 1 ten, and 10 tens make 1 hundred. The places go in groups of three, called periods: the ones, thousands and millions period.

3,482,906 people live in a city. Let’s write the number into the period table, digit by digit. We start from the right: 906 in the ones period, 482 in the thousands period, 3 in the millions period. We put a comma between the periods.

We read a number from left to right, period by period. First three million, then four hundred and eighty-two thousand, and last nine hundred and six. We don’t say the 0, but it still holds its place.

Now let’s do the opposite: two million, five hundred thousand and twenty. We write 2 in the millions period, 500 in the thousands period and 20 in the ones period. Don’t forget to write 0 in the empty places: 2,500,020.

The value of a digit depends on its place. In 4,825,130 the digit 8 is in the hundred thousands place: its value is 800,000. Let’s write the number in expanded form: 4,000,000 + 800,000 + 20,000 + 5,000 + 100 + 30.

Which stadium has more people? Stadium A has 48,250 and stadium B has 48,520. Both numbers have 5 digits. So start at the left: the first two digits are the same. The third digit is different: 2 < 5. So 48,250 < 48,520.

The Moon is about 384,400 km from the Earth. Let’s round that to the nearest hundred thousand. The number is between 300,000 and 400,000, past the halfway point of 350,000. The digit to the right of the hundred thousands place is 8: that is 5 or more, so we round up. About 400,000 km.

Summary: Digits go in groups of three called periods. We read and write a number period by period, and we put 0 in an empty place. To compare, we start at the left. To round, we look at the next digit on the right. Now try it in Number Exchange!