October 06, 2018 - 
CCNA Skills,Subnetting
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CCNA Skills,Subnetting
No comments
IPv4 Subnetting: Decimal to Binary Conversion - Subtraction Short Method
Subtraction (Short Method)
Procedure: Subtract the given number to the value of maximum number(255).
Rule:
- If the result of maximum number (255) subtracted from given number equals to zero (0) set every bit position to one(1).
n=255 255-255 = 0
| 255 | = | 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 |
| 11111111 | = | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
Binary Equivalent: 11111111
- If the result is not equal to zero (0) we will considered it as excess value. Evaluate if what particular constant value of bit position will consummate to the excess value and set it to zero(0) and the rest set it to one(1).
Given number: 217
n = 217 255-217 = 38 32 + 4 + 2 = 38
128 64 32 16 8 4 2 1
0 0 0
Note: 38 was considered here as the excess value, so the constant value of bit position that consummate the excess value will be set to zero(0) and the rest to one(1). You just need to add the constant value of bit position corresponds to one(1).
| 217 | = | 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 |
| 11011001 | = | 1 | 1 | 0 | 1 | 1 | 0 | 0 | 1 |
Binary Equivalent: 11011001