Compensated Capacitor (4.5pF) should be the same ratio of the Resistive Voltage divider. This insures Impedance matches. In this example it's a 10X probe (1M/9M+1M) = 0.1 which is 1/10th voltage.
If the internal capacitance of oscilloscope is 45pF, then you would need to divide the internal capacitance by 10 as this is the resistance ratio to keep the impedance equal.
45pF(internal capacitance)/10(Voltage divider ratio) = 4.5pF(compensating capacitor)
