Hi,
There are couple of ways to think of this ring arrangement. The first way is to think about conductance, which is the reciprocal of resistance.
1/R = 1/1.1R + 1/(1.1R + 1.1R + 1.1R ... + 1.1R)
You can see, by inspection, that the total is dominated by the first term.
In fact 10x more current flows in the first term.
In fact the resistors in the ring have 1/10 the current and 1/10 the voltage.
So the first resistor is 100x more important.
The larger the ring, the less impact the ring has on the dominant resistor.
![](https://www.eevblog.com/forum/metrology/poor-man's-resistive-ring-10k-standard/?action=dlattach;attach=405536;image)
If I change R3 by 1% the total resistance only changes by 0.009%
The other way to look at this is, simply measure and record the value of each of the individual resistors. Any combination that you do after that can be done mathematically, it does not need to be done electrically.
If the resistors are all 1% high, no matter how you combine them, mathematically or electrically, the results will be 1% high. So the worst case values are the same.
If you assume that the resistors are randomly distributed within in the tolerance band, a wild assumption, then there is some statistical benefit from averaging. But it is a bold assumption that the are truly random.
Regards,
Jay_Diddy_B