Just done. (See attachment)
Wrong (I'll check it tonight)
Try again using this and this as a guide.
Button 1 = 5V....... .= 1023 analog counts
2 = 4.892 V = 1000 analog counts
3 = 2.5 V ... = 511 analog counts
(3+4) = 0.5025 V = 514 analog counts
4 = 0.049 V = 10 analog counts
Button 3+4 is 10k in parallel with 1 Meg which results in 10k/(9900 +10 k) = 10k/19900 = 0.5025 V
As you can see, the difference between Button 3 and Button 3+4 = 2.5125628 V - 2.5 V = 0.010 V
which may be 4 analog counts which may sound the same as button 3.
The difference between 10k and 10k || 1 Meg = (10000-9900) = 100 ohms
This is the schematic you posted with your OP:
Your next post you said this:
I tryed to attach the pic but it was too large, so I'm going to write the scheme.
Nowhere did you say you were changing the schematic design.
If you are now using the ladder network then my calcs don't apply because they were done for your OP.
Your calculation for button C in your posted calculations should be: 4.9495 V
1 Meg/(10000+200 +1 Meg) = 0.9899 => 5V * 0.9899 = 4.9495 V
The others are wrong too but I don't have time to do those right now because I have to leave for work. I will say that your mistake is the denominator should be everything BELOW the resistor in question :
VB should be (R2 + R3)/((R2 + R3) +R1) =(1 Meg +10 k)/ ( (1 Meg + 10 k) + 200) = 0.9998 => 5V * 0.9998 = 4.99 V
NOT 5 mV