Subnetting Example 7

Convert decimal into binary

Example 7:

We have to find out binary value in given decimal number 30 and tell me which class it comes from ?

Note: You should always follow from left to right

Solution:

It comes from class A value given in above

Base position    2^7  2^6  2^5  2^4  2^3  2^2  2^1  2^0
Decimal value   128   64   32    16     8     4      2      1     
Binary value         0      0     0      1      1      1     1       0


After completing we can check by adding all "1"s given below;

16 + 8 + 4 + 2 = 30 

Rough note:

We can do this adding method given below;

Decimal calculations                                                         Bit in binary
128 is greater than 30                                                             off the bit
0 + 64 = 64 is greater than to 30                                             off the bit
0 + 0 + 32 = 32 is greater than 30                                           off the bit
0 + 0 + 0 + 16 = 16 is less than 30                                          on the bit
0 + 0 + 0 + 16 + 8 = 24 is less than 30                                    on the bit
0 + 0 + 0 + 16 + 8 + 4 = 28 is less than 30                              on the bit
0 + 0 + 0 + 16 + 8 + 4 + 2 = 30  is equivalent to 30                 on the bit
0 + 0 + 0 + 16 + 8 + 4 + 2 + 1 = 31 is greater than 30             off the bit

This is another way of doing through subtracting method which is done in a simple and easy way given below;

Decimal calculation                                                            Bit in binary
30 - 128 cannot be subtracted                                                 off the bit
30 - 64 cannot be subtracted                                                   off the bit
30 - 32 cannot be subtracted                                                   off the bit
30 - 16 = 14 is less than 30                                                      on the bit
14 - 8 = 6 is less than 30                                                          on the bit
6 - 4 = 2 is less than 30                                                            on the bit
2 - 2 = 0 is less than 30                                                            on the bit
0 - 1 cannot be subtracted                                                       off the bit


Therefore, this is our binary value 00011110.