Number system grade-6 ncert



Number system used in our daily life written using the symbol 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. This are known as the digits and this number system is called Hindu Arabic number system. Numbers used for counting  1, 2, 3, 4,  ……… This collection of numbers is called the counting numbers also called as set of natural numbers represented by N.

Natural number N = 1, 2, 3……

Natural number and counting number are the same.If zero 0 is included in the set of natural numbers it become the set of whole numbers represented by W.

Whole number W = 0, 1, 2, 3

Thus we can say that zero is the smallest whole number. There is another number system called Roman numeral system in which the symbols are

I,V,X,L,C

Roman numerals =  I,II, III,IV,V,VI …

We will learn Roman numeral system in detail later in this chapter.

Big numbers, Small numbers,Every day Use numbers, Introducing 6-7- and 8 digit numbers. see p-10,11.

Place value

The basis of our number system is place value. with the help of 10 numerals 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 we can write any big number. It is possible by  giving the place values to the digits in given number. The place value of a digit in a given number is the value of the digit because of the place or the position of the digit in the number. For example consider the number 7, 58, 92, 134. If you write this number in the form of Indian place value system like ones tens hundred thousand ten thousand lakh 10 lakh and crore.

Then the place value of

4 = 4 X 1 is = 4

Here the one is the place value of ones place. Same way the place value of

3 = 3 X 10 = 30

here 10  is the place value of the digit 3 because it stand on the 10th place. It can be continued to the digits 7 and we will get the complete value of the number. In words this number can be read and write as Seven Crore fifty-eight lakh ninety-two thousand one hundred thirty four . the place value of zero is always 0 irrespective of the position in the number

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