CCNA Math Practice-Binary Octets

Practice your CCNA Math by using these slides as flash cards

-Binary edition-

Common Binary to Decimal Conversions

• 00000001

• 0000 0001

• 1 * 2^0= ?

• This looks a bit odd…

• The Answer is:

• 1

Common Binary to Decimal Conversions

• 00000010

• 0000 0010

• 1 * 2^1= ?

• As small as even can be…

• The Answer is:

• 2

Common Binary to Decimal Conversions

• 00000100

• 0000 0100

• 1 * 2^2= ?

• Two squared is…

• The Answer is:

• 4

Common Binary to Decimal Conversions

• 00001000

• 0000 1000

• 1 * 2^3= ?

• The next step up would be 16…

• The Answer is:

• 8

Common Binary to Decimal Conversions

• 00010000

• 0001 0000

• 1 * 2^4= ?

• 256 / 16 = ?

• Four Squared

• The Answer is:

• 16

Common Binary to Decimal Conversions

• 00100000

• 0010 0000

• 1 * 2^5= ?

• 2 * 16 = ?

• Third largest bit value for a byte

• The Answer is:

• 32

Common Binary to Decimal Conversions

• 01000000

• 0100 0000

• 1 * 2^6= ?

• 256 / 4 = ?

• Second largest bit value for a byte

• The Answer is:

• 64

Common Binary to Decimal Conversions

• 10000000• 1000 0000• 1 * 2^7= ?• 256 / 2 = ?• The Answer is:• 128• Class B Subnets w/9 bits:• 510 Useable Subnets (Class

B w/ 9 bits subnetting) and 126 hosts per subnet

Common Binary to Decimal Conversions

• 11000000

• 1100 0000

• 128 + 64 = ?

• The Answer is:

• 192

• Class C Subnets:

• 2 Useable Subnets (ClassC) with 62 hosts per subnet

Common Binary to Decimal Conversions

• 11100000

• 1110 0000

• 256 - 32 = ?

• The Answer is:

• 224

• Class C Subnets:

• 6 Useable Subnets (ClassC) with 30 hosts per subnet

Common Binary to Decimal Conversions

• 11110000

• 1111 0000

• 256 - 16 = ?

• The Answer is:

• 240

• Class C Subnets:

• 14 Useable Subnets (ClassC) with 14 hosts per subnet

Common Binary to Decimal Conversions

• 11111000

• 1111 1000

• 2^5 Subnets created...

• 240 + 8 = ?

• The Answer is:

• 248

• Class C Subnets:

• 30 Useable Subnets (ClassC) with 6 hosts per subnet

Common Binary to Decimal Conversions

• 11111100• 1111 1100• Good Subnet Mask for Point-

to-Point Links…• 240 + 8 + 4 = ?• The Answer is:• 252• Class C Subnets:• 62 Useable Subnets (ClassC)

with 2 hosts per subnet

Common Binary to Decimal Conversions

• 11111110• 1111 1110• 240 + 8 + 4 + 2= ?• 255 - 1 = ?• The Decimal Answer is:• 254• Class B Subnets:• 126 Useable Subnets

(ClassB) with 510 hosts per subnet

Common Binary to Decimal Conversions

• 11111111

• 1111 1111

• Maximum value for a byte…

• Most Subnet Masks include one of these

• The Answer is:

• 255

• Class B Subnets:

• 254 Useable Subnets (ClassB) with 254 hosts per subnet

Common Binary to Decimal Conversions

• 00000011

• 0000 0011

• Only four could be more…

• 2 + 1 = ?

• The Answer is:

• 3

• Wildcard Mask for 255.255.255.252

Common Binary to Decimal Conversions

• 00000111

• 0000 0111

• Almost 2^3…

• 8 - 1 = ?

• The Answer is:

• 7

• Wildcard Mask for 255.255.255.248

Common Binary to Decimal Conversions

• 00001111

• 0000 1111

• Almost 16…

• 16 - 1 = ?

• The Answer is:

• 15

• Wildcard Mask for 255.255.255.240

Common Binary to Decimal Conversions

• 00011111• 0001 1111• Add all of these ones, and get

one less than next 1 is worth…

• 32 - 1 = ?• The Answer is:• 31• Wildcard Mask for

255.255.255.224

Common Binary to Decimal Conversions

• 00111111

• 0011 1111

• Almost 64…

• 64 - 1 = ?

• The Answer is:

• 63

• Wildcard Mask for 255.255.255.192

Common Binary to Decimal Conversions

• 01111111

• 0111 1111

• First Octet of the Loopback Address…

• 128 - 1 = ?

• The Answer is:

• 127

• Wildcard Mask for 255.255.255.128

Changing to a few common Decimals

• Feel free to use a sheet of paper to work on the next few slides.

• The following are a few decimals that are frequently converted to binary.

Common Decimal to Binary Conversions

• Decimal 10 to Binary

• >=128? No 0…

• >=64? No 00…

• >=32 or >=16? No 0000….

• >=8? Yes 00001…

• 10-8=2

• The answer is:

• 00001010

Common Decimal to Binary Conversions

• Decimal 168 to Binary

• >=128? Yes 1…

• 168-128=40

• >=64? No 10…

• >=32? Yes 101…

• 40-32=8

• >=16? No 1010…

• >=8? Yes

• The answer is: 10101000

Common Decimal to Binary Conversions

• Decimal 172 to Binary

• 172>=128? Yes 1…

• 172-128=44

• 44>=64? No 10…

• 44>=32? Yes 101…44-32=12

• 12>=16? No 1010…

• 12>=8? Yes 10101…

• 12-8=4

• The answer is: 10101100

CCNA Math Practice

Nice Job!

The End…for now