Units tend to have at least 9 switches, each with an 'off' and 'on' position. The switches have values as follows
1, 2, 4, 8, 16, 32, 64, 128, 256
In order to address a fixture, you have to switch on the switches so that the total value of the on switches corresponds to the address you require. Now, just to confuse things, most DIP switches are marked 'ON' and 'OFF' and depending on the circuitry used by the manufacturer 'ON' can be a '0' or '1' in the example above. Likewise 'OFF' can also be '0' or '1'. Therefore if you've set an address on a DIP switch but the unit doesn't respond it's often worth inverting the bits, making every '0' a '1' and every '1' a '0', to see if this solves the problem.
So for a value of 4 you would switch all switches apart from switch 3 (value 4) off
For a value of 5 you would switch on only switches 1 (value 1) and 3 (value 4) on
Calculating large values can seem quite complicated, however the easiest way to do this is to start and the top and work down.
If you need to find the combination of switches to get the value 200, first find the largest value below (or equal to) 200 - which would be 128. Subtract 128 from 200 - giving you 72. Now find the largest value below (or equal to) 72 - which would be 64. Subtract 64 from 72 - gives you 8 - which is one of the switches.
This means that your switches will be 8 (value 128) 7 (value 64) and 4 (value 8) 128+64+8 = 200! Job done.
As another example, to set an address of 294, set: