Start from the far right. Calculate resistors in series and replace those with a single resistor value. Then working left, calculate the resistors in parallel and replace them with a single value.
That is not all correct.
Have a look at the schematic when we draw it a little different:
Can you now tell wich resistor is in series and wich in parallel?
Riko, there appear to be three nodes which are disguised by the schematic layout HINT
Another way of looking at the network of resistors may quickly simplify how the resistances in the series and parallel configuration they are shown in. Hope that helps TommyN