I have an easier way to convert from decimal to binary. Anybody can divide by 2.

Take 129 as in your example, divide by 2 and write down what's left (1 or 0):

129
------- 1
64
------- 0
32
------- 0
16
------- 0
8
------- 0
4
------- 0
2
------- 0
1
------- 1
0

Now read from bottom to the top and write from right to left:

10000001

easy... 254:

254
------ 0
127
------ 1
63
------ 1
31
------ 1
15
------ 1
7
------ 1
3
------ 1
1
------ 1
0

Which reads 11111110