Classes of numbers

A class is a group of three place values (three digits) into which a number is split from right to left. Classes are needed for the convenience of reading and writing multi-digit numbers.

Each class contains three place values: units, tens, and hundreds. The name of a class is determined by which place values it includes: class of units, class of thousands, class of millions, and so on.

Below is a table of classes, starting with the lowest — the class of units:

• Class of units: units, tens, hundreds (1, 10, 100);
• Class of thousands: thousands, tens of thousands, hundreds of thousands (1 000, 10 000, 100 000);
• Class of millions: millions, tens of millions, hundreds of millions (1 000 000, 10 000 000, 100 000 000);
• Class of billions: billions, tens of billions, hundreds of billions (1 000 000 000, ...);
• Then come classes of trillions, quadrillions, quintillions, and so on.

To split a number into classes, count three digits from right to left and separate them with a small space.

For example, the number 1234567 is split like this: 1 234 567 — class of millions (1), class of thousands (234), class of units (567).

To read a multi-digit number, you need to:

• split the number into classes from right to left;
• read the number in each class, starting with the highest (from the left);
• after each class except the lowest, add the name of the class;
• if a place value contains 0, it is skipped when reading, but the name of the class is preserved.

Examples of reading numbers with classes:

• 25 038 — twenty-five thousand thirty-eight;
• 1 234 567 — one million two hundred thirty-four thousand five hundred sixty-seven;
• 18 000 116 — eighteen million one hundred sixteen;
• 5 000 000 099 — five billion ninety-nine.