Basic Binary Math

Basic Binary Math

• with decimal: you move through all the numerals upward until you run out

• binary: same as decimal, but utilizes 1 and 0 instead

  • Decimal to binary conversions:

  • 1 = 1

  • 2 = 10

  • Start with zero (just like decimal)

  • Next you have one, just like decimal

  • Next is 1 0, which is the same as two in decimal

  • Next one is 1 1, which is the same as three

  • Next one is 1 1 0, which is four

  • Next is 101, or 5

  • Next is 110, or 6

  • 111, or 7

  • 1000, or 8

  • 1001, or 9

  • 1010, or 10

  • 1011, or 11

• If you have 8 bits, you perform 2^8, which equals 256, which equals numbers 0-255

• Two of the most important operators are OR and AND

  • X or Y = Z

  • If either X or Y is true, then Z is true; otherwise, it’s false

• In computer logic, 1 represents true and 0 represents false

  • 0 0 = 0

  • 0 + 1 = 1

  • 1 + 0 = 1

  • 1 + 1 = 10

  • 1 AND 1 = 1

  • 1 AND 0 = 0

  • 0 AND 0= 0

  • 1 OR 0 = 1

  • 0 or 0 = 0

CIDR

• Expands on the concept of subnetting by using subnet masks to demarcate (or set off) networks

  • Demarcation point: where one network or system ends and another one begins

• Allows addresses to be defined by only two individual ID’s

• Example:

  • /24 network is 8 host bits : 2^8 = 256

  • 256 - 2 = 254

  • 254 + 254 = 508

  • /23 network is 9 host bits: 2^9 = 512

  • 512 - 2 = 510