### Convert an IP Address from Decimal to Binary Form

- The first, and probably most important step, is to put down this row of values:

128 64 32 16 8 4 2 1 - We take the IP address: 154.31.16.13 and start with the first part, which is 154.
- Question: Can I subtract 128 from 154? Answer: YES. So we assign 1 to 128.

**128**64 32 16 8 4 2 1 **1** - Question: Can I subtract 64 from 26? Answer: NO. So we assign 0 to 64.

128 **64**32 16 8 4 2 1 1 **0** - Question: Can I subtract 32 from 26? Answer: NO. So we assign 0 to 32.

128 64 **32**16 8 4 2 1 1 0 **0** - Question: Can I subtract 16 from 26? Answer: YES. So we assign 1 to 16.

128 64 32 **16**8 4 2 1 1 0 0 **1** - That will give us a remainder of 10. (26-16=10). Question: Can I subtract 8 from 10? Answer: YES. So we assign 1 to 8.

128 64 32 16 **8**4 2 1 1 0 0 1 **1** - That will give us a remainder of 2. (10-8=2). Question: Can I subtract 4 from 2? Answer: NO. So we assign 0 to 4.

128 64 32 16 8 **4**2 1 1 0 0 1 1 **0** - Question: can I subtract 2 from 2? Answer: YES. So we assign 1 to 2.

128 64 32 16 8 4 **2**1 1 0 0 1 1 0 **1** - That will give us a remainder of 0. So for the rest of the values in our row, we can assign 0.

128 64 32 16 8 4 2 **1**1 0 0 1 1 0 1 **0****10011010**converted to binary form. To double check, we take the values assigned with 1 and add them together: 128+16+8+2=154

- Question: Can I subtract 128 from 154? Answer: YES. So we assign 1 to 128.
- Our next number in the IP address is: 31. So we start with a question from step 2 again
- Can I subtract 128 from 31?

**128**64 32 16 8 4 2 1 **0** - Can I subtract 64 from 31?

128 **64**32 16 8 4 2 1 0 **0** - Can I subtract 32 from 31?

128 64 **32**16 8 4 2 1 0 0 **0** - Can I subtract 16 from 31?

128 64 32 **16**8 4 2 1 0 0 0 **1** - Can I subtract 8 from 15 (remember, it’s the remainder)?

128 64 32 16 **8**4 2 1 0 0 0 1 **1** - Can I subtract 4 from 7?

128 64 32 16 8 **4**2 1 0 0 0 1 1 **1** - Can I subtract 2 from 3?

128 64 32 16 8 4 **2**1 0 0 0 1 1 1 **1** - Can I subtract 1 from 1?

128 64 32 16 8 4 2 **1**0 0 0 1 1 1 1 **1****00011111**converted to binary form. To double check: 16+8+4+2+1=31

- Can I subtract 128 from 31?
- Next number is 16. I will perform the conversion in one step now.

128 64 32 **16**8 4 2 1 0 0 0 **1**0 0 0 0 **00010000**converted to binary form. - Next number is 13.

128 64 32 16 **8****4**2 **1**0 0 0 0 **1****1**0 **1****00001101**in binary form. To double check: 8+4+1=13

**10011010.00011111.00010000.00001101**