What is so special about being multiples of 22, 47 and 56 for standard capacitor and resistor values?
These values are chosen due to the fact that when they are plotted on a log-scale there is a linear progression in values.

See:

Why are the &quot;common&quot; resistors and capacitors rated the way they are? 

and

What is the reason that the value &quot;47&quot; is so popular in electrical engineering?

for more information.