Convert the decimal number 165 to binary

we can use the subtraction method to find this out:

create a table set out like this

  2⁷  |  2⁶  |  2⁵  |  2⁴  |  2³  |  2²  |  2¹  |  2⁰

128  |  64  |  32  |  16  |  8   |  4   |   2   |   1

       |        |       |        |       |      |        |

Now we simply take away each number.

165 - 128 = 37

37 - 64 < 0 So we ignore this one

37 - 32 = 5

5 - 16 < 0

5 - 8 < 0

5- 4 = 1

1 -2 < 0

1 - 1 = 0 

Now we fill in the table with the ones that were greater than zero with one and those not with zero

  2⁷  |  2⁶  |  2⁵  |  2⁴  |  2³  |  2²  |  2¹  |  2⁰

128  |  64  |  32  |  16  |  8   |  4   |   2   |   1

   1   |   0   |   1  |   0   |  0  |   1   |   0   |  1 

so we now know 165₁₀ = 10100101₂