And what is the problem? You corrected the reading for one month (e.g. for a value Correction). As result returned values in column 'kWh used' are changed for this month (the change value equals Correction), and for next month (the change value equals -1*Correction).



The total of 'kWh used' remains same (unless you correct entry in 1st or last row of your table), as total change will be Correction - Correction = 0

Another way to look at this: The total is 'Current rdg' from 1.03.2021 minus 'Last rdg' from 29.02.2020, i.e 15175 - 11298 =3877. Whatever happens with values between, doesn't affect this result at all!

I'm afraid the problem is in my head!!


My only defence is that advancing years seem to have dulled what powers of intellect I ever had! I confess it took me some time to follow your solution, but eventually the penny dropped!



So, very many thanks for following this, and pointing the solution to the 'non-problem' out, and apologies for wasting your and particularly Logit's time.


I really resent the loss of the time that I have spent on this, but at least my faith in Excel has now been restored, and I've learned a bit of new stuff on the way!


To Logit - thanks for your interest and persistence - you may have gathered that had you not replied to my last post, I would have given up!


So once again, very many thanks!!