The manual method
An obsolete method for the conversion of n to N scores consists of incrementing the number of matchpoints by 1
for every missing score, i.e.
S_{N}^{0} = S_{n} + N  n 
 (1) 
where:
 S_{n} = the number of matchpoints from a normal calculation with n scores
 S_{N}^{0} = the resulting increased number of matchpoints.
We express this in percentages P
_{n} en P
_{N}^{0}, and multiply left and right by 100, obtaining:
(2N  2) P_{N}^{0} = (2n  2) P_{n} + 100 ( N  n) 
 (2) 
Hence:
P_{N}^{0} = (P_{n} − 50) · 
n−1
N −1

+ 50 
 (3) 
Compared to Neuberg
P_{N} = (P_{n} − 50) · 
n−1
n

· 
N
N −1

+ 50 
 (4) 
a factor of N/n is missing from the difference with 50. The method pulls the scores too close to 50%
and this effect is larger the more N/n is larger.
A simple example:
a fouled board where 7 scores are to be split in two groups, of
3 and 4 scores, respectively.
According to this method the top with 3 scores is 66.7% and with 4 scores 75%.
With Neuberg we would have found: top with 3 scores 88.9% and with 4 scores 93.8%.
That is quite a difference. It is even better to proportionally stretch the scores to a top of 100%, than
to use this method.
Before the advent of the computer this method was generally used. As we see, mistakenly.