Subnetting Example 5

Convert decimal into binary

Example 5:

We have to find out binary value in given decimal number 130 and tell me which class it comes from ?

Note: You should always follow from left to right

Solution:

It comes from class B 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         1      0     0      0      0      0     1       0


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

128 + 2 = 130 

Rough note:

We can do this adding method given below;

Decimal calculations                                                         Bit in binary
128 is less than 130                                                                on the bit
128 + 64 = 192 is greater than to 130                                     off the bit
128 + 0 + 32 = 160 is greater than 130                                   off the bit
128 + 0 + 0 + 16 = 144 is greater than 130                             off the bit
128 + 0 + 0 + 0 + 8 = 136 is greater than 130                         off the bit
128 + 0 + 0 + 0 + 0 + 4 = 132 is greater than 130                   off the bit
128 + 0 + 0 + 0 + 0 + 0 + 2 = 130 is equivalent to 130            on the bit
128 + 0 + 0 + 0 + 0 + 0 + 0 + 1 = 129 is greater than 130       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
130 - 128 = 2 is less than 130                                                  on the bit
2 - 64 cannot be subtracted                                                     off the bit
2 - 32 cannot be subtracted                                                     off the bit
2 - 16 cannot be subtracted                                                     off the bit
2 - 8 cannot be subtracted                                                       off the bit
6 - 4 cannot be subtracted                                                    off the bit
2 - 2 = 0 is less than 130                                                          on the bit
0 - 1 cannot be subtracted                                                       off the bit


Therefore, this is our binary value 10000010