Lesson 2: Reading and Writing Large Numbers

Property

Large numbers are read by grouping digits into periods of three, starting from the right, with commas separating each period. Each period has a name (e.g., million, thousand). Read the number within each period from left to right, followed by its name, omitting the name for the ones period.

Examples

• The number $452,198$ is read as "four hundred fifty-two thousand, one hundred ninety-eight". You read the number in the thousands period ($452$) and then the number in the ones period ($198$).

Property

We will now reverse the process and write a number given in words as digits.

How to use place value to write a whole number:

1. Identify the words that indicate periods (e.g., million, thousand). Remember the ones period is never named.
2. Draw three blanks for each period to help visualize the places. Separate periods with commas.
3. Name the number in each period and place the digits in the correct place value position, using zeros as placeholders where necessary.

Examples

• 'Twenty-seven million, five hundred three thousand, ninety-one' is written as $27,503,091$. Notice the zeros used as placeholders.
• 'Eight billion, forty-two million, six hundred thousand, two hundred five' is written as $8,042,600,205$.
• 'Ninety-four thousand, fifty-three' is written as $94,053$.