## NCERT 6TH CLASS MATHEMATICS CHAPTER KNOWING OUR NUMBERS

**PREDECESSOR-SUCCESSOR**

Predecessor is 1 less than the giv**OF A NUMBER**en number. For Ex. : Predecessor of 59028 is 59027.

Successor is 1 more than the given number. Successor of 9999 is 10000.

### COMPARISON OF NUMBERS:

(a) Greater number has more number of digits.

(b) To compare two numbers having same number of digits, start comparing from the leftmost position.

If the leftmost digits are equal, move to the next digits.

Ex. Which is greater of 270346 and 48356?

Sol. 270346 has 6 digits

48356 has 5 digits

6 digits are more than 5 digits

270346 is greater than 48356

Greater number has more number of digits.

Ex. Find the greatest and the smallest numbers from the following group of numbers :

23787, 6895, 24569, 24659

Sol. Greatest number : 24659

Smallest number : 6895

### ASCENDING AND DESCENDING ORDER

#### Ascending order - arrangement of numbers from smallest to largest

#### Descending order - arrangement of numbers from largest to smallest

Ex. Arrange the following number in ascending order :

257536, 38952, 385081, 365062

Sol. The smallest number is 38952. Other numbers greater than 38952, in order are 257536, 365062 and 385081.

The numbers in ascending order are :

38952, 257536, 365062, 385081

Ex. Arrange the following numbers in descending order :

19710, 887151, 453212, 925473

Sol. The greatest number is 925473. Other numbers smaller than 925473 in order are 887151, 453212 and 19710.

The numbers in descending order are :

925473, 887151, 453212, 19710

### USE OF COMMAS

While reading and writing large numbers, it creates confusion as there are many digits in a number. To avoid making mistakes,

we use commas to divide the number into different periods. We can divide a number into different periods by using either the lndian

system of numeration or the lnternational system of numeration. But first let us learn about place value.

### PLACE VALUE

The basis of the number system is place value. It is this place value which gives value to the number.

#### Definition :

Face value of a digit in a numeral is the value of the digit itself at whatever place it may be.

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.

Place-value of a digit = Face-value of the digit × value of the place

#### Place value and Face Value :

Every digit has two values —

the place value and the face value. The face value of a digit does not change while its place value changes according to its position and number.