How we read and write numbers

To make it easier to read large numbers, we separate the figures of the numbers by commas into groups of three, counting from right to left. Each group is called the period and has its own name.

The System of numbers we use, called Arabic System, is a decimal System, that is, it is based on tens. In this System, the value a digit represents is determined by the place it has in the numbers. If a digit is moved to the left one place, the value it represents becomes ten times дs great.

Zero in the decimal System is a place-holder. In the number 30, zero shows that 3 has been moved to the left one place, thus counting tens instead of ones. The place value in numbers is shown below.

592	136,000	847,000,000	682,000,000,000
Ones	Thousands	Millions	Billions
l period	2 periods	3 periods	4 periods

These numbers are read: six hundred eighty-two billion, eight hundred forty-seven million, one hundred thirty-six thousand, five hundred and ninety-two.

All periods of a number contain three digits, or places (the first period on the left may or may not), zero is used is a place-holder.

When we want to find a single number that will represent all the numbers in a group of unequal numbers or quantities we find the average.

To find the average of a group of unequal numbers, we add the numbers and then divide their sum by the numbers of addends.

NOTES:

To make it easier to read – чтобы легче читать

ten times аs great – увеличивается в 10 раз

EXERCISES:

/. Form nouns of the following verbs:

to read, to count, to move, to place, to contain, to find, to determine, to represent.

2. Read and translate the derivatives. Mind the suffixes.

easy - easier

to add - addend

to count - counting

to represent - representative

to hold - holder

equal - unequal

3. Give English equivalents to the following:

большие числа, считая справа налево, определяется занимаемым местом в числе, десятичная система, содержит три цифры, группа неравных чисел или количеств, найти среднее арифметическое, передвигать на одно место влево

4. Give Russian equivalents to the following phrases:

separate the figures by commas, it is based on tens, as a place-holder, to find a single number, the average of a group, unequal number, the numbers of addends

5. Answer the following questions:

1. Why do we separate the figures of the numbers by commas?

2. How is each group of three figures called?

3. How is the System of numbers we use called?

4. How many digits does a period of a number contain?

5. How do we find the average of unequal numbers?

6. Make up sentences of your own using thе words and expressions given below:

Quantity, unequal, sum, to make it easier to read, to separate, thе figures of the numbers, to be determined by, ten times дs great, ten times дs small.