# How to write down numbers?

Since ancient times, people havecounting everything that surrounds them - objects, money, time and other things. Without calculations, there is nowhere to go. However, in addition, to count something, you also need to be able to correctly record the result - to write down so that it is clear to others. How to write a number correctly?

## Decimal number system

Consider the most popular in the world number system and number records - decimal. It is called so on an integer basis. 10.

Recall that a number is a quantity denotingquantity. And numbers are special signs for writing numbers. So, in the decimal system, 10 digits are used to write numbers - 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. These numbers are called Arabic. How to write numbers with these numbers?

## Rules for writing numbers in Arabic numerals

- The decimal system refers to the so-calledposition number systems. This means that each figure must be in its specific place - in its position. When the numbers are interchanged, the value of the number changes. For example, 13 and 31 are not the same.
- Each digit position in a number is called a digitof this number. Depending on the number of digits, the numbers are different in magnitude. For example, the number 13 is two-digit, since in it two digits occupy two positions, and the number 1342 is four-digit. The more bits in the number, the greater the number itself. Also do not forget that in the decimal system each category has its own name. The most common categories are the discharge of units, the discharge of tens, hundreds, thousands, tens of thousands, and so on. The bits are from right to left - that is, from the end of the number to its beginning.
- Every three categories it is customary to combine in classes. In turn, each class has its own serial number and name. For example, the first three categories, that is, the last three digits in the number - units, tens and hundreds - are combined into a class of units. The next three categories - the fourth, fifth and sixth figures from the end of the number - thousands, tens of thousands and hundreds of thousands - are combined into a class of thousands. Next come the class of millions, the class of billions, trillions and so on.

## Extended number record

This is the sum of products of coefficients on the basis of the number system in the degree of the position of the digit in the number. It sounds difficult, but in practice it's much easier.

How to write a number is extended in decimalsystem? As we recall, the basis of the system is 10. We need to decompose the number into bits and write each digit as a work of 10 to the appropriate degree. The order of units is 10 degrees to 0, tens to 101, hundreds on 102etc.

Example:

- 1345 = 5 + 40 + 300 + 1000 = 5 * 100+ 4 * 101+ 3 * 102+ 1 * 103

Using these simple rules, you can easily write down any number.