Finding the input resistance of an oscilloscope
You are measuring DC (the frequency is 0Hz). So the input resistance is equal to the impedance in this case.  

You are forming a resistive voltage divider. You know the voltage of the source, you know the value of one resistor and you know the measured voltage. That is all you need to calculate the input impedance of your scope (or the impedance of the scope+probe).







simulate this circuit &ndash; Schematic created using CircuitLab