Page 30 - Viva ICSE Computer Studies 7 : E-book

The rightmost digit of a number is called the least signifi cant digit and the leftmost digit is
called most signifi cant digit. Let’s look at an example.
6 4 2

0
2 × 10 = 2
1
4 × 10 = 40
2
6 × 10 = 600
642

The positional value of each digit increases as we move from right to left. Since its base is 10,
we multiply each digit with 10.

Binary Number System

The binary number system consists of two digits, i.e., 0 and 1. Hence, the base of binary number

system is 2. The language understood by a computer is the binary language. Therefore, the
instructions given to a computer are converted into binary language. Let’s look at an example.
1 0 1

1 × 2 0 = 1
Learn More
0 × 2 1 = 0
The base of a number system is
1 × 2 2 = 4 the number of digits used in it.

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Now, let’s learn about conversion.

Conversion of Decimal Number System into Binary Number System

Following are the steps that need to be followed to convert decimal number system into binary
number system.
Step 1: Divide the given number by 2.

Step 2: Write down the remainder and divide the quotient again by 2. The steps are repeated
till the quotient becomes zero.

Let’s understand with the help of examples.
Example 1: (25) = (?) 2 25
10 2
2 12  1
The base 10 indicates the decimal number system and
base 2 indicates the binary number system. So, you need 2 6  0
to convert decimal number system into binary number 2 3  0
system. 1  1
 
(25) = (11001) 1
10 2

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